The apportionment of seats in the House of Representatives was based on the 1800 census; both chambers had an overwhelming Democratic-Republican majority.

The count below identifies party affiliations at the beginning of the first session of this Congress.

Senators were elected by the state legislatures every two years, with one-third beginning new six-year terms with each Congress.

Preceding the names in the list below are Senate class numbers, which indicate the cycle of their election.

Of the voting members, there were 4 resignations, 4 deaths, and 2 vacancies from the beginning of this Congress.