This paper examines the hypothesis that wage discrimination emerged at the beginning of the twentieth century. I test for wage discrimination by estimating the female-male productivity ratio from samples of manufacturing firms in the northeast, and then comparing the estimated productivity ratio to the wage ratio. I find that women did not face wage discrimination in manufacturing during the nineteenth century. In 1900 there was wage discrimination against women in white-collar jobs, but not in blue-collar jobs. Wage discrimination persisted, and in 2002 the female-male wage ratio was less than the productivity ratio.