"Earth" or "The Earth" is an abandoned Gem colony planet and the primary location of Steven Universe. Earth contains many native species, with the dominant sentient species being humans. This Earth exists in an alternate universe; while it is apparently similar, there are many differences. It has a moon on which a Homeworld Gem base has been established.
Thousands of years before the current time in Steven Universe, Homeworld Gems came to Earth to exploit and colonize it. Rose Quartz believed that this was unfair to the life already present on it, and instigated the Rebellion which would drive the Homeworld Gems from Earth; in the intervening years, Earth has became the home of the Crystal Gems, who continue to protect it from Gem-based threats.
As shown in "It Could've Been Great", if the colony was finished, many more structures would have been built, including 89 Kindergartens, 67 spires, and several Galaxy Warp stations. Only 5% of this was completed according to Peridot. In addition, the Earth was to be hollowed out down to the core, with large sections of the crust removed to make the most of its resources. Due to the Rebellion, this plan was abandoned and replaced with the plans to create a geo-weapon: The Cluster.
Maps of the globe seen in the show consistently depict significant geographical differences from real life Earth:
- The Floridian Peninsula of North America is a series of small islands cut off from the mainland. Otherwise, the physical outline of North America on maps hasn't changed as drastically as some of the other continents.
- Panama does not seem to connect to South America through Colombia, instead forming a natural narrow strait where the canal is in real life.
- The eastern side of South America — loosely corresponding to Brazil — is noticeably larger than in real life, jutting out east into the South Atlantic.
- The entire western Horn of Africa, from Nigeria to Algeria and westward, is now covered by the ocean. In fact, the new west coast of this alternate Africa seems to match up with the shape of the larger east coast of South America — just as in real life, the coasts of Africa and South America visibly seem to match up, because they were pushed apart by moving tectonic plates. It's possible that the mid-Atlantic fault line that separated South America from Africa was moved further east in the Steven Universe Earth due to Gem activity.
- The Mediterranean Sea is narrower, as if the tectonic plates of Africa have moved further north, reducing the distance between Europe and Africa and thus the width of the water body.
- A large island and two smaller islands can be seen off the South Atlantic coast of eastern South America, forming an island chain between it and Africa (ending around where Nigeria would be).
- Iceland isn't visible on any map, and may not exist. Another possibility is that it was shifted south, given that there is now a very large Iceland-sized island in the archipelago between South America and Africa. Greenland exists but it seems slightly further east than in real life (Baffin Bay is larger).
- Russia is missing a huge chunk of land area in the middle of Siberia — the size of Europe. Conspicuously, it is shaped like a neat circle, and a Gem facility is in the very center of it according to the map in the moon base.
- The Indian Subcontinent has been almost bisected horizontally by the ocean, in effect making the southern half a separate island (separated from the mainland only by a long but narrow inlet).
- Similar to India, Australia has been bisected vertically by the ocean, splitting it into two separate islands. The coastlines of the eastern island are basically what they are like in real life (except for the new western coast), but much of the western island has been flooded by the ocean.
- Much of southern China's coast has been flooded by the ocean.
- A few other minor differences may also exist, but it isn't clear if they are intentional or just due to the outlines of land masses appearing blurry on a large world map in this animation style:
- The Great Lakes seem to be isolated instead of interconnected.
- Vancouver Island isn't distinctly depicted in the southwest corner of Canada.
- Japan's islands seem fused together, with the northernmost (Hokkaido) forming a land bridge to mainland Asia through Sakhalin (this might just appear this way due to the borders being blurry at a wide angle).
There are several historical differences between Earth in the show and Earth in real life.
- Delmarva is a state, in which Beach City is located. In real life this is just a term for the large peninsula on the east side of Chesapeake Bay, because it is shared by the states Delaware, Maryland and Virginia.
- The state of Pennsylvania from real life is called "Keystone".
- Kansas is a major hub of the movie industry.
- Major American cities include Charm City and Empire City.
- Money looks different. Some coins have Gadsden-like snake symbols, or pictures of a woman resembling Pearl. $1 bills have images of an upward-pointing diamond on the left and a Gadsden-like snake symbol on the right. $3 bills also exist in this world.
- Instead of the FBI, there is the Department of Justice: Federal Bureau. Their symbol has 12 stars instead of 13, and instead of a shield surrounded by laurels, there's a snake resembling the one from the Gadsden flag, accompanied by a waning crescent moon symbol.
- The Canadian flag is green and white, instead of being red and white.
- World War II never took place.
- Judging by Steven's measurement comments in "Novelty Backpack", this Earth still developed the metric system of measurements.
- In "Cry for Help", Earth is referred to as "Crystal System Colony Planet Earth".