Woman operating a card puncher, ca. 1950
This is a card puncher, an integral part of the tabulation system used by the United States Census Bureau to compile the thousands of facts gathered by the Bureau. Holes are punched in the card according to a prearranged code transferring the facts from the census questionaire into statistics.
Found at the National Archives
If my experience as a NRFU enumerator for the 2010 census was any indication, they probably are still using a few of these in back rooms somewhere…