Daria is set in the city of Lawndale; although Word of God says that it's in Maryland, this contradicts several episodes which show that its driving distance from desert and mountains. The city itself is always green, though, and it's also only a few hours drive from Boston.
Lampshaded in The Tick, in which the city is literally named "The City". This leads to landmarks being named things like "City City Hall".
Ed, Edd n Eddy takes place in a small town called Peach Creek and gives no hints as to where the town actually is.
The Grim Adventures of Billy & Mandy takes place in the fictional town of Endsville. We never get any clues about where the town is, and it doesn't help that, being one of Cartoon Network's more absurd shows, the geography of the town and the natural scenery surrounding it can readily change to fit the plot.
The Powerpuff Girls has both the City of Townsville and the Town of Citysville. The Townsville mayor puts the city at latitude 32 degrees north by longitude 212 degrees west (which doesn't exist, as longitude only goes up to 180). There is a city called Townsville in Australia, which would explain all the monsters that plague the city if the only certain thing about it wasn't that it was set in the USA.
Foster's Home for Imaginary Friends doesn't even give a name to the town where the home is, much less a general location. It is hinted, however, to take place in or near Townsville.
Frisky Dingo is set in a town which is universally referred to as "Town" — complete with extensive pauses and shifty eye movements from the characters. One episode puts them near Seattle, but this is based only on how long it took them to drive to Las Vegas. The most likely location is Atlanta, home of both the production company and [adult swim]; the freeway map seems to correspond, and the Haggar Pants Arena is a carbon copy of the Georgia Dome (albeit with a giant pair of dress pants attached to the roof).
King of the Hill is set in Arlen, Texas. Where in Texas Arlen is, however, is never made clear. It's in Heimlich County (which is also made up), and geographical details change from one episode to the next.
It's most likely somewhere near Dallas, in the DFW Metroplex. Mike Judge once lived in the Dallas suburb of Garland, which is considered the closest analogue to Arlen. Arlen is also said to be within driving distance of Arkansas and Oklahomanote Of course, being within a day's drive of Arkansas and Oklahoma doesn't do much to narrow the location within Texas down; El Paso is about as far as you can get from Arkansas and still be in Texas and it's only around 12 hours drive from Texarkana.
It may be a suburb of Austin. Strickland Propane's Real Life counterpart is based in Leander, only a short drive from Austin. Austin and Arlen even apparently share a zip code. And about 60 miles from Austin is another candidate region, Bell County, with references to the cities of Belton and Killeen.
It may be in the far south of Texas along the Gulf of Mexico. The waterpark in "Four Wave Intersection" is eerily similar to the Schlitterbahn Beach Waterpark in South Padre Island, Texas; the same episode mentions that Boomhauer was a highly-renowned surfer in Corpus Christi. "Escape from Party Island" also features a short journey to Port Aransas.
Its location relative to the Mexican border is uncertain. In "Three Days of the Kahn-Do", Hank says it's an eight-hour drive to the border, but later episodes (such as "The Perils of Polling") have characters traveling to Mexico and back in the same day.
And it did cross over with The Simpsons, but they only mentioned that Arlen is 2000 miles from Springfield, which doesn't clear anything up one way or the other.
Code Lyoko is set in an undefined location in France. Satellite shots show the action clearly taking place in the southern suburbs of Paris, but which one is not clear. The characters never name the town, nor do they refer to the river as the Seine. "The Factory" is inspired by a real Renault factory in Boulogne-Billancourt, a southern Paris suburb (it was demolished in 2004). Kadic Academy, on the other hand, was inspired by the Lycée Lakanal, based in Sceaux, further to the South. And the English dub didn't even acknowledge that it was in France.
Thomas the Tank Engine is set on the island of Sodor, which is large enough to contain mountains, lost cities, and every sort of geographical feature, sometimes contradicting itself from season to season. It seems to be broadly British in terms of scenery and architecture, with some exceptions. There is mention of an unnamed "mainland"; locomotives from there have British and American designs, although later episodes show that the "mainland" refers to mainland Britain. A few locations, including some that resemble North America or even Japan, are close enough to be reached by tunnel. The Railway Series books, though, have a rigid Fantasy World Map, which places Sodor between the Isle of Man and the Walney Channel, off of Barrow-in-Furness.
Bigg City in Tugs is never clearly given a location. One episode is called "4th of July" and features a very red-white-and-blue themed regatta, suggesting an American location. The architecture, vehicles, and generally the sheer size of the place suggests America. However, almost all the characters have British accents, and not a single one has an American accent. Wherever it is, it's at the mouth of a river near extensive logging camps, and it sometimes freezes over in winter. Word of God suggests that inspiration was taken from New York, Chicago and Baltimore.
The show itself takes place in Danville, which is somewhere in the Tri-State Area. It's never stated which Tri-State area, and later episodes suggest it was actually named after a guy called "John P. Tristate". There are also eighteen Danvilles strewn across the U.S. and Canada, so it could be any one of them. We do know that the family can drive to Mount Rushmore and back in a day, and The Pilot shows it on a map somewhere around Denver. But "Hail Doofania" has Doofenshmirtz putting his micronation in the San Francisco Bay Area (which does have a Danville), and its radio station starts with a "W" (implying that it's east of the Mississippi).
Doofenshmirtz comes from the fictional nation of Drusselstein, a tiny European Ruritania. It might be a fictional region of Germany, as Doof's dad spoke German, Doof himself has "some sort of a German accent", and he's been known to use German words on occasion (like dummkopf, meaning "idiot"). We later see that it has its own princess (whom Ferb describes as speaking with "an upper-class Drusselsteinian vocal pattern"). It might be based on a European micronation like Liechtenstein, a tiny monarchy in the Alps that uses German as an official language, but Drusselstein seems to be much a much poorer country.
The PBS cartoon series Arthur takes place in Elwood City, with no clear location. That said, its relatively easy to trace it to Elwood City, Pennsylvania, which is near Pittsburgh. The characters are within driving distance from Washington, D.C., and creator Marc Brown grew up 90 miles away in Erie, PA.
Coolsville, the hometown of the Mystery Inc. gang in A Pup Named Scooby-Doo and What's New, Scooby-Doo?. Its state is never mentioned, but it's hinted it may be in California, due to some costal settings depicted, and a rather spring-like Valentine's Day seen in "A Scooby-Doo Valentine", and any time there is snow in both series, it's outside of Coolsville in some way.
Parodied in Courage the Cowardly Dog, whose title pooch lives with his owners in the middle of a wasteland region literally called Nowhere.
Middleton in Kim Possible is apparently close enough to the heartland to be able to access Tennessee in less than thirty minutes, but it has California weather. It's been shown on maps several times — in a different location each time.
Amity Park from Danny Phantom has been hinted at to be anywhere from states like Louisiana to the northwest states like Oregon and Washington. General consensus is that it's located in the central U.S., but that doesn't explain why Casper High has "Northwestern Standardized Testing".
The city where Regular Show takes place doesn't have a clearly defined location; in fact, it appears to be named "City". It's most likely in Texas, though; radio callsigns start with "K", it seems to be close to the Mexican border, and it gets hit by a tornado at one point. Then again, "Skips v. Technology" states that the park was once a battleground during The American Revolution, putting it further east.
Metalocalypse: The location of Mordhaus, Dethklok's home, and the surrounding land is up for grabs. People have tried to get clues based on how Dethklok got to various gigs, but then it starts getting inconsistent. The only thing fans can conclude is that it isn't Los Angeles. Or the Marianas Trench. And season three reveals that Mordhaus can fly.
Rocky and Bullwinkle come from Frostbite Falls, supposedly in Minnesota, which is just about as conveniently populated as Springfield, although it is based on the real Minnesota town of International Falls (and even resides in the same county). Boris and Natasha (and their respective cohorts, superiors and employers) come from Pottsylvania, a tiny eastern European republic, which according to the live-action Movie is nestled between the two other tiny eastern European republics of Wrestlemania and Yursovania.
WordGirl's Fair City never has its location fully explained; all we know is that it's near a body of water.
Parodied in Pinky and the Brain; Brain creates his own country named Brainania, and Pinky accidentally declares war on the U.S. The U.S. immediately capitulates because they dont know where Brainania is, and they can't go to war with a country they can't find.
The city in which the Teen Titans animated series takes place is never explicitly named in the show, though it's shown to be on the west coast of the United States. In the Teen Titans Go! comic based on the animated series, it's given the moniker of Jump City. The Titans East, however, get to live in and protect "Steel City." In the Teen Titans comic that inspired the series, the team was based first in a secret location near Gotham City. Later incarnations were based in New York City and San Francisco.
Doug: Doug's hometown of Bluffington is only shown to be near Bloatsburg. However, it's likely set in Virginia, where creator Jim Jenkins grew up. In a Freeze-Frame Bonus, Skeeter has a "Visit Virginia" sign in his room, and the geography looks similar to Virginia.
Gardenia, the home town of Bloom, protagonist of Winx Club, appears to be in some English-speaking nation given the number of English signs, such as the big "Welcome to Gardenia" sign in the first episode. It certainly isn't Italy like some fans thought, since in Season 4 they had to travel to Italy in order to find a certain fairy.
In Making Fiends, there's the town of Clamburg. With clams, Puritans and a relation to Vermont and Canada, you would assume it's somewhere in New England. However, that wouldnt explain how it manages to be blazing hot in December and February. The creator lives in Los Angeles, which may explain things.
"Central City", from the two-part episode "Megatron's Master Plan", It apparently isn't that far from Autobot Headquarters, but it otherwise has no defined location.
The Autobots' crashed ship is also not given a specific location in the cartoon (although it did in the Marvel Comics, which put it near Portland, Oregon on the side of "Mount St. Hilary"). In "Cosmic Rust", though, Perceptor is left in Fox Creek Canyon, just three miles from Autobot Headquarters.
Dynomutt, Dog Wonder: The Blue Falcon and Dog Wonder, a Batman and Robin parody, come from "Big City" in an undefined state. They have a port on the ocean and are near a huge lake — an apparent joke on one of the great lakes.
League of Super Evil is set in "Metrotown". Its location is hinted at when explosions and such are seen from space, suggesting it is near Vancouver, Canada, where the show is made. And greater Vancouver also has a small neighborhood called Metrotown as well. Like Springfield, Metrotown has a statue of its founder, the aptly named "Jeremiah Metrotown".
It's hard to tell where Dora the Explorer is set. The spinoff series, Go, Diego, Go!, seems to be somewhere set in Latin America. And the spinoff Dora's Explorer Girls is equally vague; the city is unspecified, all of Dora's friends speak fluent spanglish, and it seems to be set in the same area as the original.
Johnny Test can't decide whether Porkbelly is in an unspecified American state or in Ontario.
The animated adaptation of W.I.T.C.H. never really describes Heatherfield's location either, though the English version seems to be set in a North American city that has moderate snowfall in winter and is located by the ocean. (Some have speculated that, given the coastal location and topology, Heatherfield is located in Connecticut, possibly as an alternate counterpart to the real city of New Haven.)
The Rugrats franchise is very vague about this. The characters are mostly babies who have other things to worry about anyway. The setting is discussed in-depth here, but many clues point to California, including California flags and license plates, and the ability to travel by car to Las Vegas and the Grand Canyon.
Hey Arnold! is set in the fictional city of Hillwood. There are very few clues as to where the city is located, other than the fact that there are forests and mountains as well as the beach, all within driving distance. The looks of the city itself don't provide any evidence, but the natural scenery implies that it is somewhere along the Pacific Northwest. Indeed, creator Craig Bartlett is from Seattle, and he has stated that he based Arnold's city on an amalgam of northern cities such as Seattle and Portland, though there is also a little bit of New York City thrown into the mix, particularly with the Brooklyn-style brownstones and the subway.
Another thing that suggests Brooklyn is the name of Arnold's elementary school, P.S. 118. The numbering of elementary schools is a system only used in New York City schools.
Rocket Power is a minor example. The fictional town of Ocean Shores is confirmed to be on the beaches of Southern California; it's just not confirmed exactly where it is along that coastal area (i.e. if it's closer to Los Angeles or San Diego).
The Adventures of Jimmy Neutron: Boy Genius is set in the town of Retroville. It is never actually stated where in the country Retroville is, but several hints imply it is located in Texas, including the warm climate and presence of ranches nearby. In fact, in the movie, when Goddard is converted to fly cycle mode, you can even see the "Bad Dog" vanity license plate being from Texas. However, in "Attack of the Pants", Carl at one point exclaims that his uncle is from Texas, though this might just be a throwaway line or an indication that Carl doesn't know what state he lives in. Even if Retroville is in Texas, it's still unknown what part of the state it is in, which makes a difference since Texas is the second-largest state in the union behind Alaska.
In Puppy Dog Pals , the location of the main characters' home town is purposefully in order to allow them to go to places like Hawaii, Australia, and France, and come back on the same day.
Clone High is set in the town of Exclamation, U.S.A. The references to towns such as Santa Barbara and La Puenta indicate that the town is located in California. However, the existence of "St Paul's Mattress Discounters" indicate it is possibly set in or near St. Paul, Minnesota.
The Mr. Men Show is set in Dillydale, which is located near Onionville wherever that is. It may be in California; Mr. Scatterbrain once mentions taking a wrong turn at Tahiti, and there is a bridge similar to the Golden Gate Bridge.
Fillmore!: Although X Middle School is easily large enough to qualify as a small city by itself, there's really no solid information on where it is beyond "somewhere that snows in the winter", "north of Tennessee", and "not Cleveland". Character accents don't help much, since you can find virtually any accent if you look hard enough — everything from Southern to Scottish has been used at least once. The Other Wiki puts it in or around Minneapolis.
Krazy Kat kept the location of Kokonino Kounty ambiguous for decades, until this short established it's in Idaho.
Littlest Pet Shop (2012) is set in an American city know as Downtown City. Its location in the country is unknown, but it seems to be based on New York and San Francisco.
Magic Adventures of Mumfie is all over North America. Whale mentions the U.S. Constitution in one episode, but the gang also seems to live relatively close to the North Pole.
On Toot & Puddle, Woodcock Pocket and Pocket Hollow are somewhere in the United States, far north enough that it gets snow on Christmas. All the other locations on the show are analogues of real-world locations (but with Funny Animals). Beyond that, there are no hints as to where in the United States, and some episodes even implied it was set in Canada instead.
The city in Bob's Burgers is never named, but it closely resembles San Francisco with all its old-fashioned architecture and steeply-sloped roads. Other clues, including people's accents and certain maps, would suggest it might be on the New Jersey coast. We don't even know the town's name, although the Belcher kids go to "Wagstaff school" and certain businesses are called "Oceanside". (Behind the scenes, the cast and crew call it "Seymour's Bay", after the show's editor and his editing bay that they spend a lot of time in.)
Aaahh!!! Real Monsters has a city setting that greatly resembles New York City, but there are suburban areas that suggest it's set in suburban California.
The city where Invader Zim takes place is never even named, let alone given a location. Various zoom-ins from orbit, and some supplemental material of questionable canonicity, place it anywhere from Ohio to Ontario to Quebec — the consensus is that it's somewhere in northern North America, but that's as far as it goes.
The town that's home to Sector V in Codename: Kids Next Door is never named, nor is its location stated, though there are a few hints it's in the state of Virginia.
Averted by the central town in South Park, which is located in Park County, Colorado (nearby Middle Park and North Park are rarely mentioned) and is nearby Fairplay, Fort Collins, Greeley, and most notably, Denver. Word of God has both stated it is based on Fairplay as well as childhood rumors and gossip about the real-life town of South Park. The in-universe town does suffer from Geographic Flexibility however.
Also averted in Bump in the Night, where "Made In Japan: Part 2", via an email between Squishington and Little Robot, reveals that the show takes place in San Francisco, California.
Sagwa, the Chinese Siamese Cat never gives clues as to where the Foolish Magistrate's village is. The Other Wiki guesses it's in the modern-day Fujian provinces of China and Taiwan respectively, as hinted by the scenery.
PJ Masks: In general the nameless city where the heroes reside appears to be in a European or North-American settingnote There's a Halloween Episode that shows the kids trick-or-treating, a tradition most prevalent in the US, Canada, Ireland and the UK, and during the Christmas Episode, it starts snowing, but whenever the city is seen from space, it's location differs radically between episodes. So far, it's been suggested to be in France ("Gekko's Special Rock"), India ("Owlette's Luna Trouble", & "Owlette Comes Clean"), and Panama ("Moon Madness").
My Life as a Teenage Robot takes place in the eastern half of the United States, but specifics beyond that are not available. Fan discussion on the topic suggests possible states to include New York, New Jersey, Ohio, Illinois, Michigan, Pennsylvania and Louisiana
O-Town from Rocko's Modern Life. It's never stated which state the show is set in. However, one clue from "I Have No Son!" shows it may take place in either Ohio or Michigan. Then again, Ed Bighead has said that it hasn't snowed there in years (suggesting it's further south, while Ohio and Michigan are relatively close to Canada, which would means it would logically get plenty of snow).