Rust Belt is a appropriate term used to describe the once thriving mill towns of the Midwest. As Wikipedia says:

The Rust Belt is a term for the region straddling the upper Northeastern United States, the Great Lakes, and the Midwest States, referring to economic decline, population loss, and urban decay due to the shrinking of its once powerful industrial sector…

Pittsburgh is perhaps the epitome of that term.  During my youth and beyond they were simply know as the “Steel Town”. They like many others in the area are gradually becoming a more diverse economy but Pittsburgh in particular still maintains it gritty persona… The picture taken here was from the Monongahela Incline above the city.