I didn’t see any discussion of the beginning of globalization, the decline of American manufacturing jobs, the decline of union jobs. The 70s were the beginning of the end for heavy industries in Pittsburgh.
Also, the US was one of a handful of countries not bombed during WWII and had to be very profitable from 1945 to 1960s. We were shipping cars and factory parts everywhere. By the 1970s, that advantage was disappearing.