We present the first estimates of the returns to years of schooling before 1940 using a large sample of individuals (from the 1915 Iowa State Census). The returns to a year of high school or college were substantial in 1915—about 11 percent for all males and in excess of 12 percent for young males. Education enabled individuals to enter lucrative white-collar jobs, but sizable educational wage differentials also existed within occupational groups. Returns were substantial even for those in farming. We find, using U.S. census data, that returns to education decreased between 1915 and 1940 and again during the 1940s.