An act of February 28, 1800 authorized the second census of the United States, which was to include the states and territories northwest of the Ohio River and Mississippi Territory. The census was to conclude within nine calendar months of its start.
The guidelines for the 1800 enumeration followed those of the first census, with only minor alterations in the law. John Marshall, secretary of state in 1800, was the nominal head of census operations. By early 1801, however, Marshall was chief justice of the Supreme Court. James Madison, his successor as secretary of state, oversaw the final tabulations and reported population totals to Congress and the president.
The questionnaire provided space to separately tally free white males and females in several age categories: under 10, 10 but under 15, 16 but under 25, 25 but under 45, and over 45. Indians, slaves, and free blacks were listed in single categories undivided into age groups.