nowrap | |- ! | James Cox | | Democratic-Republican | 1810 | | Incumbent died September 12, 1810.New member elected October 30–31, 1810.Democratic-Republican hold.Successor seated December 3, 1810.Successor did not run to the next term, see below. | nowrap | |- ! | John G. Jackson | | Democratic-Republican | 1803 | | Incumbent resigned September 28, 1810 after being wounded in a duel.New member elected November 1810.Democratic-Republican hold.Successor seated December 21, 1810.Successor late lost election to the next term, see below. | nowrap | |- ! | John Brown | | Democratic-Republican | 1808 | | Incumbent resigned in 1810 to become clerk of the county court of Queen Anne's County.New member elected November 15, 1810.Democratic-Republican hold.Successor seated December 3, 1810.New member was also elected by the same ballot to the next term, see below. | nowrap | |- ! | Robert Marion | | Democratic-Republican | 1804 | | Incumbent resigned December 4, 1810, having already retired.New member elected December 31, 1810.Democratic-Republican hold.Successor seated January 24, 1811. Successor had already been elected to the next term, see below. | nowrap | |} 12th Congress |- ! | John Brown | | Democratic-Republican | 1808 | | Representative-elect declined to serve to become clerk of the county court of Queen Anne's County.New member elected November 15, 1810.Democratic-Republican hold.Successor seated at the beginning of the Congress.New member was also elected by the same ballot to finish the current term, see above. | nowrap | |- ! | John Montgomery | | Democratic-Republican | 1806 | | Incumbent resigned April 29, 1811 to become Attorney General of Maryland.New member elected October 2, 1811.Democratic-Republican hold.Successor seated November 4, 1811. | nowrap | |- ! | Joseph B. Varnum | | Democratic-Republican | 1795 | | Incumbent resigned June 29, 1811 when elected U.S. senator.New member elected November 4, 1811.Democratic-Republican hold.Successor seated January 22, 1812. | nowrap | :: |} Connecticut |- ! rowspan=7 | | Lewis B. Sturges | | Federalist | 1805 | Incumbent re-elected. | rowspan=7 nowrap | |- | Jonathan O. Moseley | | Federalist | 1804 | Incumbent re-elected. |- | Benjamin Tallmadge | | Federalist | 1801 | Incumbent re-elected. |- | Epaphroditus Champion | | Federalist | 1806 | Incumbent re-elected. |- | Timothy Pitkin | | Federalist | 1805 | Incumbent re-elected. |- | Samuel W. Dana | | Federalist | 1796 | |