Аннотация:There is now an emerging consensus that over the course of U.S. economic history, multifactor productivity grew fastest over a broad plateau between 1905 and 1966, and within that period, in the two decades following 1929. This paper argues that the bulk of the achieved productivity levels in 1948 had already been attained before full scale war mobilization in 1942. It was not principally the war that laid the foundation for postwar prosperity. It was technological progress across a broad frontier of the American economy during the 1930s.