The first census began more than a year after the inauguration of President Washington and shortly before the second session of the first Congress ended.

Congress assigned responsibility for the 1790 census to the marshals of the U.S. judicial districts under an act which, with minor modifications and extensions, governed census taking through 1840.

The law required that every household be visited, that completed census schedules be posted in "two of the most public places within [each jurisdiction], there to remain for the inspection of all concerned..." and that "the aggregate amount of each description of persons" for every district be transmitted to the president.

Census Day was August 2, 1790.

The law required "That every person whose usual place of abode shall be in any family on [August 2, 1790], shall be returned as of such family; and the name of every person, who shall be an inhabitant of any district, but without a settled place of residence, shall be inserted in the column of the aforesaid schedule, which is allotted for the heads of families, in that division where he or she shall be on [August 2, 1790], and every person occasionally absent at the time of the enumeration, as belonging to that place in which he usually resides in the United States."

The U.S. Marshal for each Federal judicial district was responsible for taking the census in his district with the help of assistant marshals whom he appointed. Each took an oath or affirmation that "I will well and truly cause to be made, a just and perfect enumeration and description of all persons resident within my district, and return the same to the President of the United States, agreeably to the directions of an act of Congress, entitled, 'An act providing for the enumeration of the inhabitants of the United States,' according to the best of my ability."

Every person over age 16 was required to cooperate: "That each and every person more than sixteen years of age, whether heads of families or not ... shall be, and hereby is, obligated to render to such assistant [marshal] ... a true account, if required, to the best of his or her knowledge, of all and every person belonging to such family ... on pain of forfeiting twenty dollars...."

The census began on Monday, August 2, 1790, and was finished within 9 months.

In 1790, marshals took the census in the original 13 states; plus the districts of Kentucky, Maine, and Vermont; and the Southwest Territory (Tennessee).