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.n academic literature, the period is frequently and narrowly referred to as the post–World War II economic boom, though this term can refer to much shorter booms in particular markets. It is also known as the Long Boom, though this term is generic and can refer to other periods.