In GTA3, you were in "modern times" (i.e. Fall 2001) in Liberty City which was based on New York City. You were involved with the New York mob, including Chinatown, the Japanese, and the other ethnic groups. All of the music was fake but based on modern styles and VERY funny.

In the second game, Vice City, you stepped "back in time" to Miami in the 1980s, complete with a fully authentic soundtrack and heat-fuzzed graphics. It was truly gorgeous. In Vice City it was just like Miami Vice, but you were the bad guy in the mob, working your way up through the ranks.

Now, with San Andreas, we're in the 90s - the opening credits say you're at "Francis Intl Airport, Liberty City 1992" (flying home from Liberty City). The soundtrack is again full of real music - this time mostly rap, with a classic rock and country station thrown in. You're a young black adult male (quite a breakthrough for a commercial game!) and your mom has just been slain. You're returning back to San Andreas from Liberty City (i.e. New York City) after 5 years of being away. So you're deep in urban gang wars involving hispanics, orientals, and Russians.

The starting point - Ganton in Los Santos - is supposed to be Compton, an infamously bad neighborhood in Los Angeles. Los Santos = The Saints, Los Angeles = The Angels. Rodeo Drive for example is a famous avenue in Los Angeles. Mulholland Drive is a famous drive along the Santa Monica coastline.

The next area you unlock is the southeastern part of the map - i.e the "quiet countryside" of California.

Third is San Fierro - i.e. San Francisco. San Francisco means Saint Francis, while San Fierro means Saint Fire :) There's even a red "golden gate bridge" heading north out of town, and a Chinatown area as well as the most famous "Lombard Street", wiggling down the hillside amongst grass and trees. A famous spot in the 60s was Haight-Ashbury, also known as "Hashbury" for the drugs enjoyed there :)

The final area you get to is Las Venturas, i.e. Las Vegas, Nevada. Full of casinos and sin city stuff. Caesar's Palace has become Caligula's Palace, while the Sands appears to be the Starfish.

There's also Bone County, with the whole Area 51 thing going for it. The Hoover Dam is now the Sherman Dam :)

Grand Theft Auto San Andreas Walkthrough