Columns: District | Vacator | Reason for change | Successor | Date successor seated
New York 1st | Jonathan Havens (DR) | Died October 25, 1799 | John Smith (DR) | February 27, 1800 | Connecticut At-large | Jonathan Brace (F) | Resigned sometime in 1800 | John Cotton Smith (F) | November 17, 1800 | Virginia 13th | John Marshall (F) | Resigned June 7, 1800 to become Secretary of State | Littleton W. Tazewell (DR) | November 26, 1800 | Massachusetts 3rd | Samuel Lyman (F) | Resigned November 6, 1800 | Ebenezer Mattoon (F) | February 2, 1801 | Pennsylvania 8th | Thomas Hartley (F) | Died December 21, 1800 | John Stewart (DR) | February 3, 1801