History

The Hollerith Machine

Throughout the nineteenth century, the census became increasingly detailed and complicated. By 1880, the census, including its economic and agricultural arms, spanned several hundred questions across dozens of questionnaires. The work of processing and tabulating this data by hand was monumental. Even aided by the Seaton counting device, the tabulation and publication process for the 1880 census dragged on for most of the decade. Many planned cross-tabulations were dropped entirely.

Census Office officials realized that their problems following the 1880 census would be multiplied in 1890 – population growth alone would probably ensure that they would not be able to complete a hand-tabulated census before the end of the decade. A technological innovation saved the day.

In the late 1880’s, Herman Hollerith, a mechanical engineer who had worked as a statistician on the 1880 census, developed an electric counting machine that could process census data much faster than hand counting. The Census Office leased a fleet of Hollerith’s machines to use during the 1890 census. Despite some initial setbacks, the counting machines allowed the Census Office to process returns from the 1890 census at revolutionary speed.

Hollerith’s machine worked using punch cards. Census clerks transferred each entry on census questionnaire forms to an individual card by punching holes in certain places to indicate data points. Clerks then fed these cards individually into a circuit-closing device; wherever a hole had been punched, the circuit assigned to that data point was completed and a corresponding dial counted up by one. Hollerith also included a separate sorting tray, which helped keep the punch cards organized for different tabulations.

In 1900, the Census Office again leased electric counting machines from Herman Hollerith’s Tabulating Machine Company. By 1910, however, the new permanent agency decided not to pay Hollerith’s expensive rental fees and instead build its own version of the machine.

These machines, updated to include an automatic punch card feeder, were used to process almost all Census Bureau data through the 1940’s. By the end of World War II, however, electric counting machines were not fast and efficient enough to handle all of the data that the Census Bureau processed. Census Bureau officials set out to find a better processing device: the first computer designed for civilian use.