From Sonic Retro
The United Federation is effectively the U.S.A. of Sonic's world. Populated by humans, the Federation is led by a President who works from a building highly reminiscant of the American White House. G.U.N. appears to function as the Federation's military.
It is worth noting that the United Federation doesn't appear to be a 'World State'; in Sonic the Hedgehog (2006), Soleanna is strongly implied to be a wholly independent nation with its own monarchy. G.U.N. dosn't seem in too much of a rush to help the inhabitants of Monopole during Sonic Riders: Zero Gravity either.
- Central City (Capital)
- GUN Fortress
- Prison Island
|Locations in the Sonic the Hedgehog Game Series|
|Islands||Christmas Island | South Island | West Side Island | Angel Island | Cocoa Island | Flicky Island | Prison Island | Onyx Island | Southern Island | Starfall Islands|
|Landmarks||Never Lake | Mt. Mobius | Emerald Shrine | Tails' Workshop | Babylon Garden | Gaia Gate|
|Regions / Nations||Eggman Empire | Station Square | Mystic Ruins | United Federation | Central City | Soleanna | Monopole | City | Mystic Jungle|
|Vessels||Death Egg | Death Egg II | Egg Carrier | Space Colony ARK | Eggman Fleet|
|Planets / Planetoids||Mobius | Little Planet | Black Comet | Interstellar Amusement Park | Lost Hex|
|Dimensions||Special Stage | Maginaryworld | Sol Dimension | Arabian Nights | Twilight Cage | Grand Kingdom | White Space|