Noir Haven MUCK has its own wiki: http://noirhavenmuck.wikia.com/wiki/Connecting
Noir Haven MUCK is heavily based on a number of pop culture sources. These include such movies as 'Sin City' and 'Sky Captain and the World of Tomorrow' as well as games like 'Bioshock', and more importantly, the 'Crimson Skies' series. The latter's background matching heavily with ours.
In short, the MUCK takes place in an alternate 1930's setting in which the United States has broken apart into various squabbling nation states. This being the direct result of numerous incidents soon after World War 1 that had a greater effect than it did in real life, such as the failure of Prohibition on a national level, the onset of the Great Depression, and the 1918 Influenza pandemic. All of this, together with certain changes in the rest of the world, making for a distinctly different history than our own.