Fat City by Leonard Gardner is set primarily in Stockton, California, in the 1960s. Stockton was a dirty, dusty town clearly more on the way down than on the way up. It had a Skid Row (which was removed by 1970) and not much of anything else as its claim to fame. How appropriate, then, to have this setting for a story about two boxers, Billy and Ernie, who are going to end up on the skids, one much sooner than the other.
Think about several of the other settings in this novel. First, the YMCA, a place for those who have no place else to go. Second, a series of bars, dives, and unsavory joints which is also a place for those who have no place else to go. Even the boxing ring itself is symbolic of those who are not achieving--they might be "on the ropes" or perhaps lying unconscious on the ground.
This is a dark story of two boxers declining into self-destruction, and the setting is perfect for that kind of journey and eventual fall.