It is well-documented that, since at least the early twentieth century, U.S. income inequality has varied inversely with union density. But moving beyond this aggregate relationship has proven difficult, in part because of the absence of micro-level data on union membership prior to 1973. We...

U.S. income inequality has varied inversely with union density over the past hundred years. But moving beyond this aggregate relationship has proven difficult, in part because of limited micro-data on union membership prior to 1973. We develop a new source of micro-data on union membership...