Why was the postwar period a time of prosperity for most americans

The post–World War II economic expansion, also known as the postwar economic boom, the long boom, and the Golden Age of Capitalism, was a period of economic prosperity in the mid-20th century which occurred, following the end of World War II in 1945, and lasted until the early 1970s. It ended with the collapse of the Bretton Woods monetary system in 1971, the 1973 oil crisis, and the 1973–1974 stock market crash, which led to the 1970s recession. Narrowly defined, the period spanned from 1945 to 1952, with overall growth lasting well until 1971, though there are some debates on dating the period. Booms in individual countries differed, some starting as early as 1945, and overlapping the rise of the East Asian economies into the 1980s or 1990s.

a historian researching the immigration policies of the early 1900s would expect a source written today,rather than in 1910 to :

( a ) be more interested in objective data and statistics.