Vaarsuvius: I would venture a guess that [Roy] might be tired of the color blue by this point.
Celia: It's the only color they sell here.
So there's a place. And it only has one color. Not sixty four, not thirty two, not four, just the one color. It's everywhere. And you can't run away from it. Everywhere you go, the people will wear clothes and have hair that reflect this color scheme and no other. They must really like it.
Like Colour-Coded for Your Convenience, this trope exists mainly so that the audience knows which character belongs to which nationality. Tends to be prevalent particularly with drawn artwork where color distinction is most obvious, and thus the trope is most helpful. It also shows up from time to time in early Hollywood technicolor films- where color was the newest, greatest thing out there, and the cinematographer was going to make damn sure that the audience knew it was there.
Definitely one of those tropes which you just shouldn't think too hard about. Just enjoy the pretty, shiny color
s- you know you want to.
- In Simple Samosa, Bubblegumpur, a town made of bubble gum, is entirely pink in color.
- One issue of Swamp Thing had the titular character using plants to remake an alien world in blue.
- In Piers Anthony's Phaze series, the various Adepts decorate their estates in single colors, and even the surrounding landscape is tinted to match.
- Older Than Television: The earliest known example of this trope is in the Oz books, where the famous Emerald City is a uniform splendid shade of green, and was immortalized as such in the famous 1939 film of The Wizard of Oz. Interestingly, in the original book, the city wasn't actually green — the wizard just required that everyone wears glasses that make it look green, for his own selfish purposes. Regardless, the trope still fully applies to Munchkin Country, where houses and clothes were invariably blue, and likewise for the yellow-loving Winkies, the red-sporting Quadlings, and the purple-clad Gillikins. In some of the books, this trope goes to an extreme: even the dirt, rocks, houses, and plants take on a particular hue depending where in Oz it is.
- The Broadway adaptation The Wiz and the Retcon Wicked both adopt the glasses from the book, but oddly enough, in both cases the town is still green — perhaps for the convenience of the non-tinted-glasses-wearing audience.
- The movie version of The Wiz's Emerald City is a Single-Palette Town, but the actual color on that palette changes on occasion because of fashion. It starts green, then turns red, and then turns gold.
- Several episodes of Mister Rogers' Neighborhood featured a single-palette planet, Planet Purple, where everything was purple and the main inhabitants were blocky people who were all named Paul and Pauline, together with a Purple Panda.
- Franchise/Star Trek especially in the 90s tended to give major alien Powers with the Federation using Blues and Whites, the Klingons getting Red and Copper Greens, the Romulans getting Greys and Brighter Greens, the Cardassians getting Earthy Yellows (though early appearences also had pink thrown in, until they became major villains in a spin off and pink was difficult to take serious for what was basically Space Nazis), the Ferengi getting a brownish wet clay color, the Dominion having shades of Purple, and the Borg having Black and a sickly green colors.
- "Star Trek: Deep Space Nine" goes so far to lampshade this saying that everything on the Romulan homeworld is grey, from the buildings, the clothing, the food, and even the people (the last one is more of a dig at the Romulan's secritive and tight lipped nature making them no fun in Garrak's opinion).
- Blue by Eiffel 65 gives us this lyrical gem:
I have a blue house with a blue window
Blue is the colour of all that I wear
Blue are the streets and all the trees are too
I have a girlfriend, and she is so blue
- Urinetown typically dresses the majority of the characters in various shades of yellow. Guess why.
- Advance Wars (at least before it got Darker and Edgier) used this color scheme to help distinguish between different nations. It still does in Days Of Ruin, but it's not as clear-cut anymore. Red and Yellow both belong to the same nation, with the two colours representing two sides of a civil war, while Black is used for various groups not directly connected to a nation.
- The Happy Happy Village in EarthBound is covered and continually repainted in blue by the town when it is under the influence of the insane Happy Happy cult, which worships the colour blue. Even the livestock get painted blue. When the cult's leader is defeated, the town reverts to its normal colour scheme.
- The trope's title refers to the first generation Pokémon games where the player starts out in Pallet Town, and travels to other cities each named after a distinctive color. Provided you had a Super Game Boy accessory for the SNES or a Game Boy Color, the color of the town becomes the palette scheme (so Saffron City looks very yellow, Cinnabar Island is red, and so forth). The second generation of games' cities were similarly colored, though they were named after plants rather than colors there (though there was some overlap, like Violet City and Mahogany Town).
- And Goldenrod City, Ecruteak City, Blackthorn City...
- Possibly enforced in part by the limits of the Super Game Boy, which could assign color palettes to areas of the screen, not to individual moving objects or areas in a scrolling map. A lot of SGB games just set the whole playfield as one color.
- The abandoning of the colour-themed names was lampshaded in Pokémon Ruby and Sapphire: the First Town, Littleroot Town, was described as "A town that can't be shaded any hue."
- World of Warcraft has the two expansion races from the Burning Crusade in nearly single-color towns. The Blood Elves are in Silvermoon, which despite the name, is mainly red and gold; the crashed spaceship the Draenei call home is mainly shades of purple.
- Backyard Football has Cyan Lane, which is, of course, cyan.
- The unnamed city in Mirror's Edge has color accents, mostly from lighting or advertisement billboards, but the buildings themselves are all solid white. It's both beautiful and eerily sterile, fitting for a Crapsaccharine World police state.
- Homestuck: John Egbert's home town (Maple Valley in Washington) consists entirely of white houses with grey roofs, broken only by the enormous red Betty Crocker factory (and even that was destroyed thirteen years ago). Given that the actual Maple Valley in Washington is decidedly not constituted of all-white houses (people have actually found and photographed the house that's ostensibly John's), it's probably purely stylistic.
- The Order of the Stick:
- Azure City uses a strictly blue palette scheme. Clothes, architecture, even hair color is always disproportionately blue. Particularly odd for a series with otherwise strictly conventional hair colors for humans.
- Tsukiko is particularly notable in this regard: Because her clothes and hair are all black as part of her characterization, her eyes are two shades of blue instead, despite coming from a Far East setting.
- This appears to be religiously motivated... Or something. When a Paladin of the Sapphire Guard Falls, she is struck by lightning which not only removes her powers but leaches her all-blue outfit to beige.
- Avatar: The Last Airbender is one of the few long-running series which maintains this gimmick. Water Tribe members only use white and blue. Earth Kingdom members mostly use green, yellow, and brown, although there are some exceptions. Fire Nation members use red, brown and black. Flashbacks show the Air Nomads all wear pretty much exactly the orange and yellow outfit Aang does (their monks' habits, they're all supposed to look exactly the same). The distinct colour differences are really shown when, after a period of time dressed in the style of whichever area they're travelling through, the Gaang adopt their native styles for big events like the Day of Black Sun and Sozin's Comet.
- This is lampshaded in The Legend of Korra when Varrick mentions that a red carpet is imported from the Fire Nation because they make the best red stuff.
- In order to make important characters stand out, background crowds in Batman Beyond are colored in monochrome - usually purple or blue.
- In the film Return of the Joker, this color trend was acknowledge during a scene with Terry in a dance club with Dana, where the effect is part of the dance floor lighting and alternates between two colors. At this point, Terry has been forced to retire from being Batman by Bruce, and Terry is lit to symbolize his returned status to an ordinary scene, though the asute viewer will notice that while the two color monochrome is still happening on background characters, Terry and Dana are alternating between two different colors than the rest of the background dancers, keeping the focus on them... and then it becomes apparent that the the only other characters lit like Terry and Dana are plot relevant and are people we already met. Specifically, they're the Jokerz gang members Terry previously fought... and more importantly, They're targeting Terry, despite only encountering him as Batman.
- The Tamaranians in Teen Titans are a race of Dark Skinned Redheads who all, with the odd exception of Blackfire, dress in semi-revealing purple and silver clothing. Most of the planet's landscape seems to come in shades of purple and orange as well.
- The Transformers seem to be fond of this: Autobots paint all their stuff orange, and Decepticons color their stuff purple.
- Sometimes industrial towns will become whatever colour their industry is, due to dust, soot, etc.
- The US city of Milwaukee, Wisconsin is nicknamed Cream City, due to most of its first skyscrapers being built from a cream colored clay found on the western banks of Lake Michigan. While the city now has its share of modern glass buildings, much of the newer construction in the downtown area still looks to mimic the unique cream color. Even the city's major sports clubs (MLB's Milwaukee Brewers and the NBA's Milwaukee Bucks) have adopted cream as a team color and have introduced uniforms featuring it.
- Morocco has some wonderful examples that even forced changes in corporate branding:
- Marrakesh is predominantly in desert/peach color of its ancient walls - on its outskirts, even METRO chain had to cover their standard blue building front with desert color prop facade 
- Coastal city of Essaouira is known for its white and blue color scheme, even forcing Coca-Cola branding on restaurant's sunscreens to that color. 
- There's also Chefchaouen , is noted for its attractive blue color scheme.
- There's an upscale housing tract in the middle of Contra Costa Co., California, where all the houses are white, which makes it look like an upscale army base.
- Santa Fe, New Mexico requires that all new construction conform to the Spanish Pueblo Revival style, which, among other things, requires a lot of brown.
- Most buildings in Jerusalem, especially the older parts, are made of a specific type of limestone called "Jerusalem stone." There is a municipal law from the days of the British mandate dictating that all new buildings in Jerusalem must be faced with Jerusalem stone, to keep the city's "old" look intact.
- Williamburg, Virginia law states that all buildings must look like they are still from the colonial era, and thus a large majority, if not all, buildings are made from a brownish-colored brick. The law even applies to the College of William & Mary.
- Bath, in England. Pretty much every building in the city centre (I haven't checked them all) is made from a distinctive golden-beige stone called Bath Stone, or at least made with a similar coloured stone to maintain the effect — the best example being the new shopping centre, which was only allowed to be built in that colour. The effect from the top of the hill looking down is striking to say the least.
- Aberdeen, Scotland, known as "The Granite City" by the tourist board and "The Grey Toon" by local wags. Aberdeen grantite was one of the city's largest export commodities before the North Sea oilfields were found and tapped.
- Buildings in Boca Raton, Florida are generally expected to be pink.
- Jaipur in Rajasthan, India, is known as the Pink City. Most of the buildings are pink. The government even provides pink paint for new developments. The view from up high is pretty awesome.
- Most of the North Carolina State University main campus is made of or paved in red brick, thanks to annual donations from a local manufacturer.
- More generally, up until well into the industrial age, most towns had the majority of their buildings built from whatever material was obtainable within fifty miles or so. This tended to limit the available colour palette unless the builders were willing to fork out for importing fancier materials or buying a lot of paint, which wasn't a cheap commodity either.