The Carcer-city is a mixed prototype of the Rust Belt cities. In particular, it is dominated by the features of the East Coast and the architecture of New York. The specific prototype of Carcer city is the city of Detroit and Camden.
Also on the radio in GTA III you can hear about Carcer City, the fact that it is located nearby and about its corrupt police officers. Also in the northern part of the GTA III map there is an area closed from the player. Tonel, which, in my opinion, leads to carcer city. Liberty City is New York. In real geography West of New York is Detroit. Based on this, it can be assumed that Carcer city is a collective image of the cities of the rust belt in particular Detroit.