The US population is well over 100 million larger than in the 70s. You can't just erase changes in individual communities by looking only at national statistics. Our national economy profited just fine. Even within those national numbers, jobs that have seen significant growth line food service jobs are worse in measurable ways. The wages are significantly lower, they're less likely to provide basic benefits like health insurance, let alone paid vacation and retirement. One again, my initial assertion is that a whole lot of people don't just figure it out when part of a broad population deemed unnecessary, and the rust belt is obvious evidence of that.