| Early United States censuses were tabulated by hand, a process that took years. The electric tabulating machine, invented by American engineer Herman Hollerith and first used in the 1890 U.S. census, dramatically reduced the time and effort required to process census data. To use the machine, census clerks converted responses on census questionnaires to holes punched in predetermined locations on paper cards. When pins in the card reader passed through the holes, an electrical circuit was completed that activated the appropriate mechanical counters. |
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