Got any sources on the development of material wealth in USA potrayed in the movie?

I'm watching Forrest Gump now, and I find it quite interesting. I was wondering if anyone had any sources (preferably online) about the development of material wealth (or wealth in general) in USA as portrayed in the movie and the time period it is set. I'm not to familiar with the development, although I know it got better. Therefore I would like to hear your views as well. :)