A lot of things changed around 1970. That year looks like a major historical fulcrum for the USA.
1970 was approximately (within a few years):
1. The year manufacturing employment started to stagnate (later to decline).
2. The Great Compression reached its peak.
3. The Great Stagnation began.
4. Roe v. Wade was passed
5. Women entering workforce en masse.
6. Historic increase in immigration begins.
7. End of Bretton Woods.
8. Beginning of large trade deficits.
That is from Famulus.