We estimate trends in intergenerational economic mobility by matching men in the Census to synthetic parents in the prior generation. We find that mobility increased from 1950 to 1980 but has declined sharply since 1980. While our estimator places greater weight on location effects than the standard intergenerational coefficient, the size of the bias appears to be small. Our preferred results suggest that earnings are regressing to the mean more slowly now than at any time since World War II, causing economic differences between families to become more persistent. However, current rates of positional mobility appear historically normal. (Contains 4 tables, 15 figures, and 38 footnotes.)