Well, actually, the Germans and the Japanese built the US middle class.   At the end of WWII, the US was the only major power that wasn't either bankrupt or whose infrastructure was rubble.   We had a good run until we started to get some meaningful competition, and did some stupid things, in the mid-seventies.    Union membership in the US when the NLRA was passed in '35 was about 7%.   The run-up to WWII and forced unionization by the War Labor Board dramatically increased unionization.   Since the end of WWII, private-sector unionization has steadily declined to its historic level of 7-8% of the workforce.   In reality there is almost no true private sector unionization as most non-public employee unionization is in "Third Sector" industries that hold government monopolies or rely on government funding or complex permitting, e.g., utilities, some transportation, aerospace/aviation, publicly funded construction, etc.