Local governments across the United States annually hold tax auctions, in which unpaid property tax bills are sold to investors, who in turn obtain the right to charge interest on those debts or acquire title to tax delinquent property. In Chicago, reforms to Illinois’s tax sales law in 1951 gave rise to a class of investors who reaped millions through fees, interest payments, and, in some cases, acquisition of real estate for the price of a single property tax bill. Tax buying thrived as rates of property tax delinquency rose sharply in the 1970s, especially in the city’s African American neighborhoods, which suffered from discriminatory overassessment. As the city’s fiscal situation worsened, tax buyers wielded greater influence over tax policy and administration. Tax sales shed new light on the making of contemporary municipal fiscal policies and administrative practices, and highlight broader features of capitalism and the state in modern America.