The decennial census has always required a large workforce to visit and collect data from households. Between 1790 to 1870, the duty of collecting census data fell upon the U.S. Marshals. A March 3, 1879 act replaced the U.S. Marshals with specially hired and trained census-takers to conduct the 1880 and subsequent censuses.
During the early censuses, U.S. Marshalls received little training or instruction on how to collect census data. In fact, it was not until 1830 that marshals even received printed shedules on which to record households' responses. The marshals often received limited instruction from the census acts passed prior to each census.
Beginning with the 1880 census, specially hired and trained census-takers replaced the U.S. marshals. Door-to-door census by temporary census-takers was the primary method of conducting the census until the U.S. Census Bureau began mailing questionnaires to households in 1960.
As more and more households received and returned their questionnaires by mail, the role of census-taker changed. Today, the majority of households are counted by mailed questionnaires. Census-takers visit places frequented by transient households (shelters and soup kitchens, campsites, etc.) and households that do not return their mailed questionnaires (during the "Nonresponse Follow-Up" phase of the census). As a result, the "Instructions to Enumerators" provided here include the congressional acts U.S. marshalls reviewed during the early census, specially-published instructions for door-to-door census, and lastly, guides used for the limited number of personal interviews conducted during nonresponse follow-up operations.