Columns: District | Vacator | Reason for change | Successor | Date successor seated
Maryland 5th | Vacant | Rep. Stephen W. Gambrill died in previous Congress | Lansdale Sasscer (D) | January 12, 1943 | Arkansas 4th | William B. Cravens (D) | Died January 13, 1939 | William F. Cravens (D) | September 12, 1939 | Pennsylvania 4th | J. Burrwood Daly (D) | Died March 12, 1939 | John E. Sheridan (D) | November 7, 1939 | Tennessee 6th | Clarence W. Turner (D) | Died March 23, 1939 | W. Wirt Courtney (D) | May 11, 1939 | New York 34th | Bert Lord (R) | Died May 24, 1939 | Edwin A. Hall (R) | November 7, 1939 | Georgia 4th | Emmett M. Owen (D) | Died June 21, 1939 | A. Sidney Camp (D) | August 1, 1939 | Wisconsin 3rd | Harry W. Griswold (R) | Died July 4, 1939 | Vacant until the next Congress | Vacant until the next Congress | Tennessee 3rd | Sam D. McReynolds (D) | Died July 11, 1939 | Estes Kefauver (D) | September 13, 1939 | California 18th | Thomas M. Eaton (R) | Died September 16, 1939 | Vacant until the next Congress | Vacant until the next Congress | South Carolina 1st | Thomas S. McMillan (D) | Died September 29, 1939 | Clara G. McMillan (D) | November 7, 1939 | Ohio 22nd | Chester C. Bolton (R) | Died October 29, 1939 | Frances P. Bolton (R) | February 27, 1940 | Tennessee 2nd | J. Will Taylor (R) | Died November 14, 1939 | John Jennings, Jr. (R) | December 30, 1939 | Puerto Rico At-large | Santiago Iglesias (Coalitionist) | Died December 5, 1939 | Bolívar Pagán (Socialist) | December 26, 1939 | Colorado 3rd | John A. Martin (D) | Died December 23, 1939 | William E. Burney (D) | November 5, 1940 | Michigan 5th | Carl E. Mapes (R) | Died December 12, 1939 | Bartel J. Jonkman (R) | February 19, 1940 | New York 14th | William I. Sirovich (D) | Died December 17, 1939 | Morris M. Edelstein (D) | February 6, 1940 | Ohio 17th | William A. Ashbrook (D) | Died January 1, 1940 | J. Harry McGregor (R) | February 27, 1940 | Nebraska 1st | George H. Heinke (R) | Died January 2, 1940 | John H. Sweet (R) | April 19, 1940 | New York 31st | Wallace E. Pierce (R) | Died January 3, 1940 | Clarence E. Kilburn (R) | February 13, 1940 | New York 22nd | Edward W. Curley (D) | Died January 6, 1940 | Walter A. Lynch (D) | February 20, 1940 | Iowa 6th | Cassius C. Dowell (R) | Died February 4, 1940 | Robert K. Goodwin (R) | March 5, 1940 | Maine 2nd | Clyde Smith (R) | Died April 8, 1940 | Margaret Chase Smith (R) | June 3, 1940 | Georgia 8th | W. Benjamin Gibbs (D) | Died August 7, 1940 | Florence Reville Gibbs (D) | October 1, 1940 | New Jersey 8th | George N. Seger (R) | Died August 26, 1940 | Vacant until the next Congress | Vacant until the next Congress