The paper reports evidence on historical variation in levels of inter-industry factor mobility in the U.S economy. It examines inter-industry variation in wages and profits in the manufacturing sector from 1820 to 1990. The findings indicate that early stages of industrialization increased labor and capital mobility in the 19th century as costs of transportation and communication fell and the demand for unskilled labor rose; later stages of industrialization, on the other hand, which involved greater reliance on very specific forms of human and physical capital, led to a decline in inter-industry factor mobility during most of the 20th century.