Census pantograph and 1930s keypunches

A U.S. Census Bureau clerk (left) prepares punch cards using a pantograph similar to that developed by Herman Hollerith for the 1890 Census, while a second clerk (right) uses a 1930s key punch to perform the same task more quickly. The agency used punch cards to record and sort data using mechanical tabulators based on Hollerith’s designs until replacing them with computers and magnetic computer tape in the 1950s.