Last week the National Archives released the complete 1940 census online, the result of a three-year digitization project involving a host of 21st-century technologies. But the analog census seven decades ago was a technological feat in its own right, employing machines to tabulate and analyze the data. Statistical compilation from the 1870 census took seven years to complete. With the two machines (the one on the left dating to the late 19th century and the one on the right more modern and compact), officials expected everything to wrap up in less than three years. The two women operating the machines are Ann Oliver (left) and Virginia Balinger. They fed the machines punched cards, the analog translations of handwritten census forms.

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Image: Library of Congress.