By allowing each machine to be driven by its own power source, electric motors spurred the development  1  This discussion is based on Roger W. Ferguson, Jr., and William L. Wascher, "Lessons from the Past Productivity Booms (139 KB PDF)," Journal of Economic Perspectives, vol. 18, (Spring 2004).
BIS Review 40/2004  1  of complex and more-productive configurations of machinery, such as the assembly line. Finally, the productivity gains of the 1950s and 1960s had their roots in a wide range of technological innovations made during the 1930s as well as in research sponsored by the military during World War II.