I read the other entries and felt compelled to hold up Granite City as an example of decline in the USA. The town is stratified big time. The haves and the have nots are segregated physically. If you have a good job you're fine, and if you don't you're screwed. There is also a major disparity in levels of education, and a hell of a lot of people that seem to always want to fight.
My family is from Lincoln Place, a declining part of the western edge of the city. It was home to a diverse immigrant community of Armenians, Hungarians, Macedonians, Croatians, and Mexicans, clustered around American Steel. The hood was always hardscrabble, but the old timers had a lot of pride. The ethnic folks' kids improved their station and mainly moved out. The neighborhood is still home to the Mexican Honarary Commission, and several of my family members.
The town used to have three mills going gangbusters, now there's one big one and a much smaller one. The decline in the steel industry led to a population crash from 40K in the late seventies to 31K now. Much of the population is of advanced age.
If the GC Steel ever closes, the town will simply fall into the toilet.