America’s post-war (1945 to 1970) golden period was a time of low immigration with that immigration concentrated on White Europeans.
This was a time of widely shared prosperity with a broad and deep middle class and a narrowing of wealth gaps. During this time America built the Hoover dam, created the Interstate Highway system, and put a man on the Moon. We did all of this with a ‘white bread’ population and low immigration.
The post-1970 high ‘diverse’ immigration period has brought a narrowed less secure middle class, collapsing infrastructure, and the need for Russian rockets to launch our satellites.
Wasn't Hoover dam built as a make-work project during the Depression?