->''"The clock in San Dimas is always running."''
-->-- '''Rufus''', ''Film/BillAndTedsExcellentAdventure''

San Dimas Time is a device in a TimeTravel story that allows a writer to add some against-the-clock tension -- in spite of how little sense that makes when you have time travel at your disposal.

When San Dimas Time is in effect, events in two different time periods affect each other a fixed time period apart -- for example, if you go back in time a year and change something, the change will only [[DelayedRippleEffect take effect a year after it takes place]], and vice versa. This means that if you have to fix something in the past, and the villain is racing to do something in the future to stop you, you still have a limited time in the past to solve the problem before the future villain's actions render your actions moot.

This, of course, raises the [[ElephantInTheLivingRoom obvious question]]; if you need more time to do what you need to do, and you have a time machine, why don't you just... go back in time? This question is rarely answered, [[VoodooShark at least satisfactorily]]. If it is addressed, it's often blamed on the TimeyWimeyBall, the need to avoid {{Temporal Paradox}}es, or just prevent the obvious questions when you complete your journey, arrive at the same time you've left, but appear to have aged several years. It's also useful when you're communicating live with someone in a different time period (like some sort of inter-temporal telephone), to ensure no bizarre relativistic effects.

San Dimas Time is related to but distinct from a PortalToThePast, where the time travel mechanism ''itself'' is restrained in what you can do -- you can only travel through time by specific increments, or [[UnstuckInTime you only have a limited period]] before the time travel stops working. MeanwhileInTheFuture is a narrative version of this; the two eras do not actually affect each other, but we're seeing time pass within them at the same rate.

See also FantasticTimeManagement and TrickedOutTime, which are ways to solve this problem. Contrast TakeYourTime, where you have all the time you need even though there ''should'' be time pressure.

----
!!Examples

[[foldercontrol]]

[[folder:Anime and Manga]]
* Chapter 21 of the ''Anime/DragonBallSuper'' manga {{retcon}}s the series' time travel mechanism to work on San Dimas Time, just to add drama to the situation. It's particularly baffling because it explicitly did not work that way in ''Anime/DragonBallZ'', nor does it work that way in the anime.
* In the ''Anime/InazumaEleven'' movie ''Saikyō Gundan Ōga Shūrai'', a future organization travels back in time to prevent the events of the first season from happening, in an effort to make soccer SeriousBusiness and make future people tougher. Endou's [[KidFromTheFuture great-grandson]] Kanon follows them back in time to stop them. Both parties seem to think San Dimas Time is in effect despite not having any reason to think so. Kanon even apologizes for showing up late to the final match, in spite of being able to travel through time.
* ''Anime/TimePaladinSakura'' seems to run on San Dimas Time; for instance, Sakura hears that her base is being wrecked in the past and only sees it wrecked after that happens.
[[/folder]]

[[folder: Comic Books ]]
* Early [[UsefulNotes/TheSilverAgeOfComicBooks Silver Age]] ''ComicBook/{{Legion of Super-Heroes}}'' stories are full of such moments, with characters crossing back and forth between the 20th and 30th centuries as if they were just on the other side of town. "Oh no! We're too late!"
** Subverted in a 1990s ''Superboy'' story, when the Legion lose a member in the timestream. The Legionnaires insist they need to find her as soon as possible, before something happens to her, to which Brainiac 5 replies, "Doesn't anyone realize we're talking about time travel?"
** In the Legion's tie-in story to ComicBook/FinalCrisis, Superboy [[spoiler:burns a line across Superboy-Prime's chest, and the same mark suddenly appears on the chest of Prime's future counterpart, Time Trapper]].
* The DCU's ''ComicBook/CrisisOnInfiniteEarths'' enacted its RedSkiesCrossover in this way, as the anti-matter wall that was destroying the Multiverse by going ''backwards'' in time was causing the sky in each continuity in to turn red at the same rate, regardless of when these stories took place.
* ''WesternAnimation/DonaldDuck'' time travel stories generally uses this rule, at least in the sense of characters having a limited period of time to hang around in the past. Sometimes it's justified by the time travel mechanism; the machine didn't actually travel with them, but just sent them to a time and location, so they had to prearrange a time when the machine would pull them back to the present.
** [[http://coa.inducks.org/story.php?c=D+95022 One story]] presents a particularly convoluted example. Gyro Gearloose accidentally sends an atomic bomb back to the prehistoric era and sends Donald and his nephews to retrieve it. They can still contact Gyro from the past, and the same amount of time has passed since the journey for each party. A time paradox also causes Earth to [[DelayedRippleEffect slowly disappear at the same rate in both eras]] as the bomb starts to wreak havoc and history tries to fix itself, before Donald succeeds and the universe un-corrects itself. Gyro tries to explain this mechanism but only manages to give Donald and his nephews a headache.
** [[http://coa.inducks.org/story.php?c=I+TL+2458-5 This comic]] has WesternAnimation/MickeyMouse and WesternAnimation/{{Goofy}} are badgered into traveling back in time to see the finals of an Aztec proto-soccer tournament, jump the same length of time to hours after they left, and find that Zapotec has recorded the game for them in the meantime.
* In ''ComicBook/DaysOfFuturePast'', Kitty Pryde is psychically sent back in time to her younger body before the BadFuture happens. While she's in the past trying to prevent the assassination that would cause the BadFuture, her friends lug her unconscious body around trying to keep it safe from Sentinel attacks. They don't know for sure if San Dimas Time is in effect, but they don't want to take the chance. They wonder if their timeline will be erased when Kitty completes her mission. In the end it isn't, creating an AlternateTimeline.
* ''ComicBook/ScoobyDooTeamUp'': In "Scooby-Doo, When Are You?", a scientist from ''[[WesternAnimation/TheFlintstones the Flintstones' ]]'' time tests a TimeMachine by pulling Mystery, Inc. from the "future" and tells them it'll likely take from three to four years before he's able to send them back. Shaggy is worried because he forgot to water his plants. The Great Gazoo tries to use his power to send them back but he "overshoots" and sends them to ''WesternAnimation/TheJetsons''. An archaeological team working for Mr. Spacely had already found the time machine by then and George Jetson uses it to send them to the very point in time [[AvertedTrope it took them from in the first place]].
[[/folder]]

[[folder:Fan Works]]
* In ''FanFic/SailorMoonZ'' "episodes" 10 and 11, a botched attempt to have the modern Inner senshi quintet observe their past selves leads not only to this but also to a switch between past and present selves that marks the point where the "series" takes a HotterAndSexier turn.
* ''FanFic/ForeverJanette'' by [[RichsComixBlog Rich Morris]] averts ''Series/DoctorWho'''s tendency to use San Dimas Time (see below) by featuring the Fifth Doctor meeting the Master from the Seventh Doctor's timeline.
* In ''[[https://www.fanfiction.net/s/3643368/1/Back-I-Go Back I Go]]'', Harry does a number of things in the past which alter the present, but instead of people's memories changing all at once, they get an "update" after certain significant past interactions with Harry.
* Discussed in ''ComicBook/{{Supergirl}}'' fanfic ''Fanfic/HellsisterTrilogy''. Kara knows she can technically spend as long as she wants in the 31st century, but she feels she needs to get back to her normal life.
-->He was only wearing white shorts and was half-covered by the sheet of the bed in her room at Legion Headquarters. "You're really going back today?"\\
Kara Zor-El walked back into the bedchamber. Hairbrush still in one hand, she bent and hugged him. "I have to, Devian. I still live in the 20th Century. Got to get to work. I was on my way there when the Legion summoned me." She felt the firmness of his naked chest against her and was very glad she had become his lover. Her empty hand stroked the contours of his back. His arms were holding her as well, and she bit her lip to keep passion from overruling judgment.\\
She could stay with him for a year here, easily. Two years. Longer. But she had a life, otherwhen, and she had to get back to it.
* In the ''Fanfic/PonyPOVSeries'', it's eventually revealed that [[spoiler:Shining Armor's arc, taking place several years in the past, is running simultaneously to the main story, meaning ForegoneConclusion is ''not'' in effect]]. The reason for this is that [[spoiler:Shining Armor literally did not exist until the day Twilight went to Ponyville, having been inserted into the timeline to be the [[ForWantOfANail nail between the main world]] and [[BadFuture Dark World]], and thus he's experiencing time differently]]. This continues until [[spoiler:his place in the timeline is cemented, causing the present to wait for him to "catch up" before moving forward]].
* In ''[[http://archiveofourown.org/works/202671/chapters/300232 The Western Sky - Series 2]]'', Sally spends two weeks in the "present" of an alternate timeline trying to SetRightWhatOnceWentWrong and when she returns to the original timeline, Harry states that she's been missing for two weeks.
* In ''[[https://www.fanfiction.net/s/9316405/2/Time-Altered Time Altered]]'':
-->'''Dumbledore:''' It would seem to me after what you have described that you somehow traveled through a wormhole. William Halleck wrote a book once telling of how when he was eleven he fell through a wormhole and was pushed forward into the future. He said that he lived there for three years until another wormhole found him and he was brought back to his original time. Three years' time had passed in his old time without him but other than that not much was different.
[[/folder]]

[[folder:Film]]
* ''Film/BillAndTedsExcellentAdventure'' is the TropeNamer, even though this doesn't seem to be an actual limitation to the story's time travel mechanism. Rufus tells the eponymous Bill and Ted that no matter when they are, "the clock in San Dimas is always running", so they need to hurry to get their research done in the past. But the boys bounce all over time and even encounter themselves by arriving a day earlier than they meant to, so there's no reason to suspect that they can't just give themselves more time if they needed it. The [[FanWank prevailing fan theory]] is that Rufus was [[MotivationalLie lying]] -- he just told them that because he knew they were [[TheDitz dumb teenagers]] who needed sufficient motivation to actually work on their project. By [[Film/BillAndTedsBogusJourney the second film]], this is averted completely, as the boys spend a year and a half traveling through time and arrive back a second after they left.
* In ''Film/AustinPowersTheSpyWhoShaggedMe'', Fat Bastard encounters a HumanPopsicle Austin in 1969 and starts [[UnusualEuphemism draining his mojo]]. It seems to affect Austin exactly 30 years in the future when he's unfrozen in 1999, as his mojo suddenly starts draining at the same rate that Fat Bastard is draining his mojo in the past -- while he's in the middle of shagging Dr. Evil's assassin.
* ''Franchise/BackToTheFuture'' doesn't use this trope; it derives its tension from an inability to activate the time machine or a need to avoid a {{temporal paradox}}. But since time travel is a novel, scary, and untested phenomenon, sometimes the characters behave as if San Dimas Time is in effect:
** In the first ''Film/BackToTheFuture'', Marty laments that he'll be too late to warn Doc of his fate once he gets back to 1985 -- until he realizes that he has a time machine, and he has all the time in the world. Unfortunately, he doesn't think to give himself any more than just 10 minutes, and the [=DeLorean's=] engine is [[MyCarHatesMe not obliging]], so he ''still'' doesn't make it in time to save Doc. [[spoiler:Fortunately, Doc decided to [[TrickedOutTime bend the laws of history]] and read Marty's letter from 1955 anyway.]]
** In ''Film/BackToTheFuturePartII'', Doc rushes to get Marty in position to pretend to be his son in 2015, and his watch is synced up to 2015 time to make sure he's got his timing right. But if he's wrong, he's got a time machine and can start again -- except he doesn't seem to realize this as an option. One [[EpilepticTrees theory]] is that he has to improvise because encountering Jennifer in 1985 and accidentally showing her the time machine shot his original plan completely to hell.
* In ''Film/BestDefense'', Dudley Moore races against the clock to install a cooling system in a tank, just in the nick of time to save Eddie Murphy... ten years later. It turns out that there's no actual San Dimas Time in effect -- it's just poorly executed MeanwhileInTheFuture, and the film's withholding this from the audience was not well received.
* In ''Film/{{Frequency}}'', 1969 time and 1999 time seems to be hooked up and run concurrently during the duration of the ''aurora borealis''.
* The first sequel to ''Film/{{Halloweentown}}'' appears to have a restriction of this sort. The characters travel back in time, but have until midnight "their time" to return to the present. Even the ''process'' of time travel takes San Dimas Time, as one character comments, "It's almost twelve, and so far we're only at the 1970s."
* The edited version of ''Film/HighlanderIITheQuickening'' replaced "The Planet Zeist" with "The Distant Past" and walked right into this trope.
* The film version of ''Film/ASoundOfThunder'' overlaps this with a PortalToThePast. The time machine opens a single "gate", and while it's open, the people who go through are experiencing the past at the same rate that people in the future/present are experiencing it. Part of the climax is that, after everything goes horribly (and predictably) wrong, they have to go back in time to the ''same'' period and stop the screw-up. All this is pretty in synch with various hypothetical methods of time travel. The ''ways'' it affects the future is... jarring to say the least.
* In ''Film/StargateContinuum'', Ba'al's changes to the timeline cause the Tok'ra and Vala to disappear one by one just before his execution in the present. Cam Mitchell, trying to stop him in the climax, needs to get to the moment of a particular solar flare, but can't get there because the TimeyWimeyBall won't let him. But then he defies the trope and just [[TheSlowPath waits a few years]].
* In ''Film/TeenageMutantNinjaTurtlesIII'', the time traveling scepter (in the present) only has enough power to work five times in sixty hours, after which it is destroyed, rendering even the fully intact scepter in 1603 Japan useless as well.
* In ''Film/XMenDaysOfFuturePast'', time travel works this way because it's MentalTimeTravel; Kitty can only send Logan's consciousness back to his 1973 body, and she has to work constantly to keep him there. Time passes at the same rate in both eras relative to each other (as shown when Charles hijacks the connection to talk to his past self). The problem is that the 2023 X-Men are under attack by an army of Sentinels, and the time travel mechanism was their early warning system and is now preoccupied, which provides a time limit for Logan to SetRightWhatOnceWentWrong in 1973.
[[/folder]]

[[folder:Literature]]
* In Creator/IsaacAsimov's ''Literature/TheEndOfEternity'', an organization is able to travel through our time, while maintaining a wholly separate, normal, only-goes-forward-at-one-second-per-second time of their own. This necessitates the inventions of the words "upwhen" and "downwhen" for the time travelers to be able to talk about the past and the future as it exists in "our" time, instead of their own future and past. They refer to this as "physiotime", as it reflects the aging process, not the passage of time.
* In the ''Literature/{{Xanth}}'' series, the time periods that the isthmus is connected to all move forward at the same rate as Xanth. If a Xanthian was to spend a year in TheDarkAges, they would return to Xanth a year later. This spell was done that way so Xanth can trade with other time periods, and the rules of time travel clearly don't require it, as unescorted non-Xanthians end up randomly dislocated in time going in, for security purposes. Technically, nothing stops Xanthians from going to Earth, going back into Xanth, redirecting the isthmus to reconnect to Earth an hour earlier, going back to Earth, and meeting themselves there, and then coming back escorted by themselves so that one of them ends up in the wrong time, but the isthmus connection is ''incredibly'' vague about what time period it connects to, and getting somewhere near the right century is amazing, so that would not be possible in practice (to say nothing of the paradoxes).
* The time travel in Creator/HPLovecraft's ''Literature/TheShadowOutOfTime'' seems to work this way. When a member of the Great Race of Yith takes over a human body in the present, the human host's mind in turn goes back in time to the body of the creature that possessed him. The creature then spends several years in the person's body studying the history and culture of the era, and "meanwhile" the person spends equal amount of time in the creature's body, forced to write down all he knows about his own civilization. It's left unclear if this is a law of time travel or just a matter of convenience.
* In ''Literature/ByHisBootstraps'' by Creator/RobertAHeinlein, Diktor apparently tried to invoke San Dimas Time on his predecessor self, but was rebuffed by with the line, "How can we waste time when we have ''this''?" So he smoothed it over with fast talk and invocation of authority. It was worth a shot, since the protagonist is [[spoiler:essentially every single important character in the story]] -- his own personal clock keeps ticking, meaning things need to happen precisely when they did/will/must happen.
* The whole of the ''[[Literature/ThePendragonAdventure Pendragon]]'' series, by D.J. [=MacHale=], runs on San Dimas Time. The Travelers ostensibly arrive exactly when necessary to stop the evil plot, but half of the territories are separated solely by a time difference, and that the villain doesn't have to follow any of the same rules. It takes some time for the Travelers wise up and realize that [[BigBad Saint Daine]] can undo any repair of a critical point, simply by going back to it.
* In the later books of Creator/StephenKing's ''Franchise/TheDarkTower'' series (which involves dimensional as well as time travel), there is revealed to be a Keystone Earth in which time always moves forward and [[RaceAgainstTheClock the clock is always ticking]]. Time does not move forward at a constant rate, though, periodically "lurching" forward in relation to the universe in which the majority of the action takes place. The mechanism is a direct result of Roland's own world having "[[AfterTheEnd moved on]]".
* Creator/OctaviaButler's ''Literature/{{Kindred}}'' combines this with NarniaTime; whenever the protagonist is dragged back in time to save Rufus, the time that passes in the present before her return is compressed proportionally to how long she spends in the past. When, for example, she spends a few minutes in the past, she disappears in the present for a mere second or two, but when she accidentally leaves her husband in the past, she spends three weeks in the present before going back and learning that her husband has been stranded for over five years.
* The short story ''[[http://www.tor.com/stories/2011/08/wikihistory "Wikihistory"]]'' by Desmond Warzel would seem to operate on San Dimas time; otherwise there would be no suspense regarding [=AsianAvenger's=] return.
* Averted in ''Literature/TimeTravelersNeverDie'' by Creator/JackMcDevitt. The protagonists realize early on that the clock is ''not'' always running in San Dimas, and use that fact to prepare for time trips or to bail themselves out of dicey situations.
* ''Literature/{{Discworld}}'':
** {{Lampshaded}} in ''Discworld/ThiefOfTime'', which tells the story of an anxious man with time travel powers hurrying to find a midwife for his wife's difficult labour, even as he easily travels through several decades during his search.
** In ''Discworld/NightWatch'', Lu Tze makes it explicitly clear that time travel works in a series of elastic time loops, which will snap back into a single timeline, the nature of that timeline depending on the actions of the person doing the time travel. However, this concept starts to [[TimeTravelTenseTrouble hurt Vimes' brain]], so Lu Tze suggests that he just [[DiscussedTrope think of everything]] happening one thing after the other.
* Robert Asprin's ''Literature/TimeScout'' series works on this. Each portal moves one a fixed distance back in time from when you entered it, so a week away in the past is a week in the future and vice versa.
* In Edward Ormondroyd's ''Time at the Top'', Susan Shaw spends a couple of days in the past and returns to find her father and the cook/housekeeper frantic about her disappearance.
* In ''Literature/SonicTheHedgehogInTheFourthDimension'', Dr. Robotnik [[EvilGloating brags]] that the heroic duo has only fifteen minutes left to exist because his robots in the past have found (and are about to kill) the first evolved hedgehog and fox on the planet.
* ''Franchise/DoctorWhoExpandedUniverse'':
** The ''Literature/EighthDoctorAdventures'' novel ''Emotional Chemistry'' maintains a continuous narrative crossing between three time periods, with four separate means of time travel, and only one point at which one of the characters is "out of sync" with the others.
** In the ''Literature/DoctorWhoMissingAdventures'' novel ''Goth Opera'', the villainess, a Time Lady, muses on how if she wanted to face the Doctor, the rules of meeting other Time Lords (see below) dictate that she would likely be facing the (then-current) [[{{Chessmaster}} Seventh Doctor]], and she cycles through all of the Doctor's regenerations looking for an easier matchup, even though this breaks the established rules. (She settles on the Fifth Doctor, who's [[BewareTheNiceOnes still too much for her]].)
* Averted in Scott Meyer's ''[[Literature/{{Magic20}} An Unwelcome Quest]]''. Early in the novel, Todd kidnaps five of the wizards and drops Jeff off a cliff to his death. None of the wizards are too concerned, since they believe that they can just travel through time and come back to that point later. Todd points out two flaws in that analysis: ''(a)'' he made sure to watch Jeff hit the bottom of the cliff, ensuring that no one [[TimeTravelTenseTrouble did/will]] save him, and ''(b)'' he's not planning to let the rest of them leave alive either. In order to engineer a StableTimeLoop, they have to save Jeff by making Todd ''think'' he succeeded, and they only have one attempt at it.
* ZigZagged in ''Literature/BlackoutAllClear'' by Connie Willis. A group of historians stranded in UsefulNotes/WorldWarII-era England worry about meeting up with recovery teams at the right place at the right time. Some of them (sometimes belatedly) remember that the team back home can take all the time they need to find them, because they have time travel. Except they still don't turn up when they're supposed to.
[[/folder]]

[[folder: Live Action TV ]]
* ''Series/DoctorWho'', being the progenitor of the TimeyWimeyBall, will occasionally use San Dimas Time to explain whatever else is going on. One consistent rule (which became AscendedFanon) is that all [=TARDISes=] and everyone in them run on "Gallifrey Time", which forces everything else into San Dimas Time. The effect of this is that if the Doctor meets another Time Lord -- or one of his [[TheNthDoctor other incarnations]] -- they will always remember events in the same order, even if the number of years in between may differ. But there are always Timey-Wimey complications and exceptions:
** In [[Recap/DoctorWhoS13E3PyramidsOfMars "Pyramids of Mars"]], the Doctor has only a narrow window of opportunity to trap Sutekh in the spacetime tunnel. Even if he were to use the TARDIS to return to Earth at a point hours or weeks earlier, he'd only wind up waiting around for the few minutes when Sutekh is ''in'' the tunnel, and can therefore be trapped. The fact that he rushes to get it done immediately is more an indication of his excitement level than fear of wasting precious San Dimas Time.
** The Doctor will often be out of sync with other time travelers who are using non-Gallifreyan technology, like Captain Jack's vortex manipulator.
** River Song, despite being [[spoiler:kind of a Time Lord]], routinely experiences events in a different order from the Doctor, sometimes (but not always) in reverse order. They have to sync diaries to figure out what the other knows. The first meeting from the Doctor's perspective is the weirdest (and saddest), because when he doesn't recognize her at all, she knows (because he [[TimeTravelTenseTrouble told/will tell]] her) that [[spoiler:she dies at the end of that meeting]].
** The Time War appears to work in a fashion like this, although it's never properly explained; at the beginning of [[Recap/DoctorWhoS30E17E18TheEndOfTime "The End of Time"]], Ood Sigma warns the Doctor that "events that have happened are happening ''now''", alerting the Doctor that something is ''very'' wrong and causing him to rush to the TARDIS and get back to the twenty-first century. (He's just a bit too late.) It turns out this derives from [[spoiler:the Doctor's solution to the Time War -- lock them in time while he [[KillItWithFire destroys them all]], technically ending the war but not forcing them -- or himself -- to face the music]]. Out of universe, this trope is required to make the Doctor LastOfHisKind without running into any pre-war Time Lords.
** Time is sufficiently broken in [[Recap/DoctorWhoS31E12ThePandoricaOpens "The Pandorica Opens"]]/[[Recap/DoctorWhoS31E13TheBigBang "The Big Bang"]] that it seems to be running in San Dimas Time in ''two'' directions at once, explaining how the TARDIS can go around in time when [[spoiler:it's also exploding and causing every star in the universe to supernova simultaneously at every point in time]].
** The ''Literature/DoctorWhoNewAdventures'' novels expand on how "Gallifrey Time" works. What we know as time is called "Outer Time", and all Time Lords, as well as all [=TARDISes=] and their inhabitants, are fundamentally bound to what Gallifreyans call "Inner Time", which is an entirely separate dimension from what we call "time". Time Lords can travel freely in Outer Time, but never in Inner Time, which always passes at the same rate for everyone. This allows them to reconcile their timelines when they interact with each other. In fact, Outer Time -- and what us {{Muggles}} would call "reality" as a whole -- is an artificial construct created by the Seven Founders to make sense of physics.
* In ''Series/FamilyMatters'', Urkel's time machine appears to run on San Dimas Time; in the second episode in which it appears, Urkel and Carl are trapped in the past, with Harriet back home in 1997 wondering where they had run off to.
* The 1950s ''[[Series/FlashGordon1954 Flash Gordon]]'' TV show:
** In one episode the main characters have to travel back to the present day to disarm a bomb set to go off in their time... ''1000 years later''.
** In another episode, after superluminal travel sends the protagonist back in time, he is still able to communicate with the base ''by radio'', lining them up on San Dimas Time.
* In the final episode of ''Series/GoodnightSweetheart'', Gary [[spoiler:ends up stuck in the past and writes a message to Ron in the present on the wall of his flat. Rather than the message having been there throughout the intervening decades, it materialises slowly in the present as Gary writes it in 1945.]]
* In ''Series/{{Journeyman}}'', Dan doesn't have any control over when he time-travels, and the time he is missing from the present is never proportional to how long he was in the past. However, Dan lives in the 2000s and his fellow time-traveler Livia lives in the 1940s. Their lives appear to be synchronized and they experience their encounters, which occur in various time periods, in the same order.
* ''Series/KamenRiderDenO'' uses a variation: the [=DenLiner=] (and all other time trains) can only travel between two points in time, the "destination" on the Rider Ticket and the point of origin. The show thus has a few episodes where the heroes have to rush to get back to the present in time to prevent another crisis.
* In ''Series/LegendsOfTomorrow'':
** The Season One finale has [[BigBad Vandal Savage]] planning to set off three different {{Doomsday Device}}s in three different time periods [[LogicBomb simultaneously]] -- presumably, this is in relation to San Dimas Time. The heroes stop him by splitting into three teams, each heading to a different time period and killing Savage in three time periods, also simultaneously. The problem is that Savage is immortal; but they solve this by exposing him to radiation from all three {{Doomsday Device}}s simultaneously, rendering him mortal. It's [[MST3KMantra best not to think about it too hard]].
** In the Season Three episode "Phone Home", Professor Martin Stein is revealed to have built a communicator capable of broadcasting through time so that he can keep tabs on his pregnant daughter, who is about to give birth to his first grandchild in 2017. There is a good deal of urgency about getting him to the hospital in time to be there for the birth, despite his living on a ship that travels through time.
** It's actually relatively consistant that "time" keeps flowing for the Legends even while they're running around time. Whenever they go to the "present" it's always the current time according to other shows, even the couple times they've taken a break they're returned to whatever the current date is in Flash and Arrow rather than the night Rip first recruited them in 2016, with them being away for all the months that have passed since that date. This is probably to keep things in sync with the rest of the Arrowverse.
* A variation occurs in season 5 of ''Series/{{Lost}}''. The Oceanic Six leave the Island in 2004, just as the people left on the Island (Sawyer, Juliet, Jin, Miles, Daniel, and Charlotte) start traveling through time, eventually ending up in 1974. When the Oceanic Six return to the Island in 2007, they are sent back in time to 1977. From everyone's perspective, it has been three years since they last met. Since then, everyone who enters or leaves the island is displaced permanently in time, but everyone who encounters each other after having done so will do so according to San Dimas Time.
* ''Series/MightyMorphinPowerRangers'': the episode "Wild West Rangers" has Kimberly thrown back to TheWildWest, leaving Billy and the remaining Rangers trying to retrieve her. Billy specifically states at one point, "It's a paradox. Our world won't change until Kimberly battles the monster in her time," implying the two timelines had become synchronised.
* The events of ''Series/PowerRangersTimeForce'' are built on this trope. Ransik goes back in time to the year 2001, and the Rangers follow him a few minutes later. If the Power Rangers universe didn't run on San Dimas Time, the year 3000 would have been instantly altered at that point; there would have been nobody in 2001 to stop him. Later, it's explained that the things the Rangers and Ransik do in 2001 alter the future on a 1:1 ratio. This also explains why some times the Megazord is unavailable due to repair, despite the fact that, by all reasons, Time Force should be able to take whatever time they need to repair the Zords before sending them back in time to when they are needed. In the following season, which takes place in 2002, the CrossOver has the Rangers contact 3001, a year later from the future timeline.
* In the ''Series/NightGallery'' story "The Little Black Bag", people from the future discover that a medical bag has been accidentally sent back in time to the audience's present. They then deactivate the "futuristic" abilities of the tools in the bag, but with a gap between when the bag was found and the tools were deactivated similar to the time between when the bag was lost and it was realized to have been lost. This is unfortunate for [[spoiler: the guy being operated on with a scalpel from the bag at the time]], for one.
* In ''Series/QuantumLeap'', from the moment Ziggy locates where and when Sam has leaped, the past and the future appear to be in sync. This becomes a problem when events in the future distract Al while Sam is in the middle of something. However, in several episodes Al comments that they have spent weeks looking for Sam since his last leap, while Sam has only experienced a few hours. This suggests that once Ziggy has located Sam, there has to be a concerted effort to keep their respective time periods in sync.
* ''Franchise/StarTrek'':
** ZigZagged in the ''Series/StarTrekEnterprise'' episode "Future Tense". The crew encounters a time traveler from the future and activates his "homing beacon", so his people from the future can find him. Once it's activated, he and all his devices are instantly transported back home. Captain Archer notes that once they got the beacon's signal, the future people could take all the time they need to retrieve him. Except if the beacon is activated in the past, the future people should see it at any time -- even [[MindScrew before the ship travels back in time to begin with]].
** Used interestingly in the ''Series/StarTrekDeepSpaceNine'' episode "Time's Orphan", where an eight-year-old Molly O'Brien falls into a time portal, which closes after her and forces the crew to spend a few hours reactivating it. By the time they do, [[YearInsideHourOutside she's aged ten years]] and turned into a WildChild from being stranded alone in the wilderness. They acknowledge the possibility of simply retrieving her from an earlier time period, but find that ethically problematic because that would RetGone the Molly in front of them. They try to readjust her to "normal" life but [[spoiler:she responds violently]], and they conclude the best thing to do is [[spoiler:send her back to the wilderness she came from and give up on seeing her again]]. Then she turns out to [[spoiler:have been sent to a period shortly after her eight-year-old self arrived and sends her past self back through the portal, reuniting the O'Briens with their young daughter]].
* This appears to be how time travel works in ''Series/{{Timeless}}''. The control room at Mason Industries always has a mission clock running above it, which appears to match the time the team spends in the past. There's also lots of urgency about sending the Lifeboat back in time as soon as the Mothership's timejump is detected. Were this trope not in effect, Flynn's changes to the timeline would have been instantaneous to anyone in the present the moment he went back into the past.
* This appears to be the case in ''Series/TimeTrax''. Since the show can't seem to decide if Darien is really in the past or in a time-shifted parallel universe, this may or may not be justified. Although several episodes suggest the latter is the case, they do occasionally contact Darien's superior by leaving coded messages in the classifieds, which are received in order and not simultaneously.
* Most episodes of ''Series/{{Voyagers}}'' start with Jeffrey and Bogg arriving in one time period, jumping to another time period (usually to escape a sticky situation), and then returning to the first time period to fix history. This often results in Bogg wanting to hang around in the second time period (usually because of a woman) while Jeffrey anxiously tries to impress on him the urgency of needing to go back to the first time period "before it's too late", despite how little sense this makes.
* ''Series/WhereInTimeIsCarmenSandiego'' imposed a twenty-two minute time limit from the moment that the time-travelling villains stole a historical artifact/landmark to when history would be irreversibly altered. They never twig that they could go back in time to just before the theft in order to stop it, but that would ruin the quiz show a bit.
* In ''Series/MakingHistory2017'', Chris assumes they can just go back to shortly after they left. Dan informs him that the time machine doesn't work that way; however long you stay in the past, that's how much you're gone in the present. This information comes at the worst possible time, after spending days working for UsefulNotes/AlCapone, and Chris frets about all the work days he's missed.
* For [[TechnoBabble technobabbly reasons]], people in ''{{Series/Travelers}}'' can't be sent further back than the time of the last arrival. That enforces a crude synchronization between the twenty-first century and the BadFuture - the latest Traveler to arrive will always have been sent back from a later time than all the Travelers who arrived before them, creating the illusion that the two time periods are happening in parallel.
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[[folder: Tabletop Games ]]
* ''TabletopGame/{{GURPS}} Time Travel'''s standard scenario states that you can only travel to time "windows", about three months apart (and slowly growing farther apart), that are dragged forward as normal time passes. Why this happens, along with what happened at the point the windows initially extended from, is an unexplained mystery. This setting also has time moving at different rates in different time periods, meaning ten days in the past equals a single day in the present. However, this is only one of several options provided by GURPS Time Travel -- it has rules to cover nearly every version of TimeTravel on this site.
* The ''TabletopGame/TeenageMutantNinjaTurtlesAndOtherStrangeness'' supplement "Transdimensional TMNT" had a surprisingly complex justification for San Dimas Time that involved the time stream coiling around itself in predictable patterns and jumping from coil to coil where they touch.
* ''TabletopGame/FengShui'' has a reasonably sensible take on this trope: the various time periods, of which there are currently four, are linked together by portals through the Netherworld, and time in all four locations moves at the same pace. This has the effect, among other things, of making TrickedOutTime much harder for the players to manage -- although if they have a decent Feng Shui site and are reasonably clever, they might just pull it off.
[[/folder]]

[[folder:Video Games]]
* ''VideoGame/{{Achron}}'' involves this, though more for gameplay purposes. The present is always moving, and any viewing of the past or future will by default involve the player moving through time at the same speed as the present. Changing any specific point in time also becomes harder as the present moves away from it, for [[CompetitiveBalance balance reasons]]. However, the changes made in the past are periodically propagated faster than the player can go by [[DelayedRippleEffect timewaves]], and the player can control their rate of movement through time. For example, fast forwarding will cause one to catch up to the present eventually, propagating changes along the way. This means that if someone else changes the past, you only have a certain amount of time to SetRightWhatOnceWentWrong, or else the change becomes irrevocable.
* In ''[[VideoGame/FreedomForce Freedom Force vs. The Third Reich]]'', some of the team members end up in TheForties, but others remain in psychic contact via Mentor and appear to be experiencing the flow of time at the same rate.
* ''VideoGame/ShadowOfDestiny'' uses San Dimas Time; since the time in the present is counting down to the time of your inevitable death, it puts a time limit on all the puzzles you need to solve in the past, even this doesn't make much sense.
* ''VideoGame/TheJourneymanProject'' series of computer games are all dependent on this trope. Whenever something in the past is altered, it creates "temporal ripples" that take a certain amount of San Dimas Time to reach the present, allowing the TimePolice enough time to go back and fix the distortions before they reach their present.
* ''VideoGame/ChronoTrigger'' typically does this with [[PortalToThePast Portals To The Past]], but later in the game, you acquire a TimeMachine, and travel with it still inexplicably works the same way. Interestingly, {{fanon}} holds that the TimeMachine is based on the preexisting [[PortalToThePast portals between time periods]]. Here's the [[http://www.chronocompendium.com/Term/Principles_of_Time_and_Dimensional_Travel.html relevant article]].
* HandWaved in ''VideoGame/WhereInTimeIsCarmenSandiego1997'' where it's stated that legal time travel has to be cleared with a federal agency, and thus each Chrono-Skimmer will return to the present after a certain number of hours of machine use. The villains have no such problem.
* Time travel in ''VideoGame/SonicTheHedgehog2006'' is exemplified by the line, "Oh no! We've got to hurry!" -- if you don't complete the level in time, something bad happens in another time period. Interestingly, [[spoiler:Sonic actually ends up being too late for one event -- which he fixes by simply hopping back in time a few minutes]].
* The mandatory surfing stages in ''Mario's Time Machine'' for the Super NES are timed, meaning that San Dimas Time is in effect. The only gameplay downside to letting time run out, though, is that you get fewer bonus points.
-->'''WebVideo/TheAngryVideoGameNerd:''' And how ironic is that, that there's a time limit to go back in time?!
* In ''VideoGame/DayOfTheTentacle'', the three main characters are stuck in the present, 200 years in the past, and 200 years in the future respectively, and events that happen in the past affect the characters in the future in San Dimas Time. For example, one character in the past can convince George Washington to cut down a tree in the yard, causing the tree to vanish into a stump in future timelines and another character (who is stuck to the tree by her underwear) to fall on her ass.
* In one level in ''VideoGame/{{Chronotron}}'', your time machine is on a lever controlled by an inaccessible button with a bomb on it. You must complete whatever you need to do before the bomb explodes, the lever goes away, and your time machine falls into oblivion. And, you can't just arrive earlier, because San Dimas Time doesn't work that way.
* Used as a plot point in ''[[VideoGame/TheLegendOfZeldaOracleGames The Legend of Zelda: Oracle of Ages]]'', as the BigBad has stopped time at high noon around the construction site for the final dungeon. No matter how quickly you progress, [[YouCantThwartStageOne you can't stop the tower from being built.]] However, rather than appear completed instantaneously to your present self, the tower being built in the past progresses in increments as you progress through the plot.
* The high concept of ''VideoGame/SpiderManEdgeOfTime'': Actions in the present alter the future, but they do so "simultaneously" in relation to the PortalToThePast; if SpiderMan can't stop the giant robot from ever being built "before" it kills SpiderMan [[ComicBook/Marvel2099 2099]], then it's too late. Miguel {{handwave}}s this as a side effect of the permanent connection between the two time periods; Peter {{lampshades}} that it still doesn't make any sense.
* In ''VideoGame/TimeLord'', the clock is always running in 2999, and you have one year to SaveTheWorld by traveling through four historical time zones.
* ZigZagged in ''VideoGame/RadiantHistoria''. While Stocke can only move to certain fixed "nodes" in the timeline, each one is static, and traveling there will cause the same set of events to occur unless he does something to change it, and exploiting this effect is how he achieves his goals. However, Stocke's personal timeline is constant; he takes his items, knowledge, and wounds with him every time he jumps around.
* In ''VideoGame/GhostTrick'', every time Sissel goes time-travelling and returns to the present after averting someone's fate, it's always later than when he left (e.g., he left at 7:02 and returned at 7:21). [[FridgeLogic The use of this trope doesn't make sense upon analysis, though]], because Sissel is always forced to travel to the same point in history: four minutes before a given person's death. He could wait ten hours to time travel and save their life, and it wouldn't make a difference in the success of said mission.
* In ''VideoGame/WorldOfWarcraft'', the Deaths of Chromie scenario introduced in 7.2.5 works like this. Chromie is going to die at a specific time, and you only have fifteen minutes to fix everything. You could try to go back earlier, except a master of time travel is blocking your attempts to do so. In any event, you can retry the scenario as many times as you want.
[[/folder]]

[[folder:Visual Novels]]
* In ''VisualNovel/NineHoursNinePersonsNineDoors'', the way morphogenetic fields work is that the transmitter and the receiver have to be experiencing the same situation, so even after [[spoiler:Akane]] removes the usual limitation that they have to be experiencing the situation simultaneously and links up with Junpei nine years later, the two Nonary Games still have to remain perfectly synced up. Therefore, despite [[spoiler:not actually being on a sinking ship]] Junpei still has to solve all of the puzzles within nine hours or else [[spoiler:Akane]] will die nine years in the past.
[[/folder]]

[[folder:Web Comics]]
* ''WebComic/{{Superosity}}'' doesn't have San Dimas Time but illustrates a good reason to enforce it -- the characters have aged while time-travelling, and although they return to ThePresent a millisecond after they left, they worry about having aged (and whether they have to change their birthdays).
* Played with [[http://www.the-whiteboard.com/autowb183.html here]] in ''Webcomic/TheWhiteboard'', with an experimental paintball marker that fires a paintball through a time warp.
* ''Webcomic/SluggyFreelance''
** At the end of ''The Storm Breaker Saga'', it's revealed the time travelling in this and previous stories uses some form of San Dimas Time. [[spoiler:When the demon K'Z'K was accidentally blasted into the past (taking Gwynn's soul with him), he "cut a noticeable trail" through time and space. Zoe and Torg follow him along the same trail, arriving some time after K'Z'K. They defeat K'Z'K and free Gwynn's soul, which travels back to the present and revives Gwynn's comatose body.]] All this implies that San Dimas Time is in effect. But when [[spoiler:Gwynn tells Riff and Dr. Schlock where Torg and Zoe are, they follow the trail her soul took and arrive moments after K'Z'K is defeated]], which is ''not'' exactly San Dimas Time, but possibly {{justified|trope}} with the idea that [[spoiler:Gwynn's soul operates differently, perhaps because it has to maintain sync with her physical body]].
** In "Mohkadun", [[spoiler:Gwynn and Siphaniana swap souls, which spend an extended period of time in each other's timeline]], syncing up according to San Dimas Time. The mechanism that [[spoiler:switches them back and forth]] is determined from both ends by a magic ritual designed for that purpose.
* ''Webcomic/{{Homestuck}}'' calls this [[http://mspaintadventures.wikia.com/wiki/Circumstantial_simultaneity circumstantial simultaneity]]. It expresses how two events can happen "at the same time", even if they're ''not'' happening at the same time or if the events are in different timelines altogether.
** Characters called Exiles operate computers which monitor specific people from 413 years in the past. Several times, Exiles try to assist those they monitor, but they never attempt to send messages any time except ''exactly'' 413 years in the past, even when sending a message sooner or later could save lives.
** The big End of Act 5 Flash animation, [S] Cascade, involves no less than four different chronologies happening "simultaneously". For example, one of the major villains, [[spoiler:Jack Noir, destroys a universe from the outside shortly after that universe was created. At the "same time", the Scratch is initiated to reset said universe, while Jack's past self in the future of the same universe is trying to escape from its destruction. This universe then explodes at the "same time" as another universe, even though the second universe existed ''before'' the first one, and the first universe was destroyed over 1024 years before the second universe itself explodes.]]
** In Act 6, a few characters use a chat program that lets them communicate with characters living centuries in the past (well, in the past from the future characters' perspectives) or across realities. These copies of the program are designed to run on San Dimas Time to prevent synchronization issues.
* In ''WebComic/ManlyGuysDoingManlyThings'', San Dimas Time is enforced over long periods even though it's not a law of time travel, because otherwise leaving for months and coming back five minutes after you left can make things rather troubling.
[[/folder]]

[[folder:Web Original]]
* Parodied in the ''Podcast/ThrillingAdventureHour'' and "The Cross-Time Adventures of Colonel Tick-Tock", when Queen Victoria repeatedly requires Colonel Tick-Tock to immediately leave to travel back in time to fix a problem, despite also saying that "Time is the one luxury we ''do'' have." It's lampshaded in one appearance where Tick-Tock's wife Constance asks "Couldn't he leave at any time?" The Colonel explains that it's "Quite the opposite. Were I to finish this biscuit, I would be far too late!"
[[/folder]]

[[folder:Western Animation]]
* In an episode of the ''WesternAnimation/MenInBlack'' AnimatedAdaptation, Jay and Kay have to travel back in time to TheWildWest, when an energy-absorbing alien who's about to cause havoc in modern time was still vulnerable. According to some TechnoBabble, the past and present move at the same rate, so Jay and Kay only have a few hours to finish the job over a century ago, or else the alien will destroy a city, which theoretically wouldn't revert to normal even after the alien is killed in its larval stage over a hundred years ago. Nevertheless, when Jay and Kay find themselves running out of time and in need of backup in the past, they can use a device (which [[TheSlowPath only travels through time at the speed of regular time]]) that will remain dormant until the corresponding present (as opposed to the present from the beginning of the episode) and then relay a message to the rest of the team describing the problem and requesting backup.
* In the ''WesternAnimation/DuckTales1987'' episode "Time is Money", the characters appear to have at least a vague awareness that TimeTravel doesn't work this way, given that they discuss going back in time to change events that occurred during the episode. They never do this, however, and past time periods do appear to be synchronized with the present.
* ''{{WesternAnimation/Superfriends}}'':
** In one episode, Aquaman and a couple of others are trapped in the distant past. He decides to bury his communicator under the future site of the Hall of Justice and set the emergency signal. The signal isn't detected until after his and several other teams get trapped in different eras and the rest of the team has begun looking for them.
** In another episode, the Superfriends travel back in time to stop the time-traveling villians from meddling with their origins. Flash worries that he might have arrived too late to stop them, apparently not realizing that if he is, he can just go back further in time.
* An episode of ''WesternAnimation/BikerMiceFromMars'' had the BigBad travelling into the past to demolish the city by digging giant holes where it would be built. Whenever he finished digging a hole, it would appear "at the same time" in the future in the middle of the city.
* In ''WesternAnimation/BeastWars'', The Planet Buster is blown up over prehistoric Earth, unleashing the Quantum Wave. Half a season later, the Transformers realize the Quantum Wave travels in space and time. It should reach Cybertron around the time period they come from (the 24th Century). The wave in fact hits right about the same length of time after the Maximals left their century as they have spent in the past, establishing San Dimas Time. Now, the Tripredacus Council sends an agent back in the past, to assist the Maximals to apprehend the Predacons, figuring out the time period from the Quantum Wave. Because of San Dimas Time, he arrives several months after the Planet Buster's detonation, as opposed to some time before then (which could easily have {{retcon}}ned the second season otherwise).
* In the ''WesternAnimation/JackieChanAdventures'' episode "J2", Jade's FutureBadass self travels back in time to prevent [[BigBad Shendu's]] release in her time. She explains that because time is still moving forward in both eras, they have to destroy the artifacts before midnight, since future Jackie and Uncle are being held prisoner and Shendu can finish them off when he's freed. The artifacts are destroyed ''after'' midnight but [[SubvertedTrope Shendu's newfound freedom is undone.]]
* In ''WesternAnimation/AmericanDad'''s first Christmas episode, it's established that [[YetAnotherChristmasCarol the Ghost of Christmas Past]] visiting Stan has only just gotten the job, and Stan is actually her first client. Her time magic doesn't have any established limitations, so it seems to run on San Dimas Time just because she's not good enough at temporal magic to realize that it doesn't have to. She ends up late to stop Stan's meddling in the timeline because she had to get Francine's help in finding him and wound up lost in the Jurassic era. At the end of the episode, she gives Stan a present while saying she was just able to get to the mall in time to buy it.
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