The first census was conducted a little more than a year after the inauguration of President Washington, during the second session of the first Congress. The responsibility for the 1790 Census was initially given to the U.S. marshals. 

There were only six questions at the time, and they were questions on gender, race, the relationship to the head of household, the name of the head of household, and then the number of slaves each household had. The marshals in some states went beyond these questions and also collected data on occupations as well as the number of dwellings in each city or town.

Technically, starting with the initial census, The U.S. Constitution only requires that the decennial (10-year) census be a count of the population. Following the first census in 1790, however, the need for more useful information about the U.S. population became more and more evident.

As the nineteenth century continued, the census steadily expanded. By the turn of the century, the demographic, economic, and agricultural parts of the census collected information on an increasing number of topics. The work of processing all these data kept the then temporary Census Office open for many of the the decades following the 1880 and 1890 censuses.

Finally recognizing the ever-growing complexity of the census, Congress enacted legislation that created a permanent Census Office within the Department of the Interior in March of 1902. Then, on July 1, 1902, the U.S. Census Bureau came under the leadership of William Rush Merriam and officially opened its doors.