| nowrap | |- ! | Otto Passman | | Democratic | 1946 | Incumbent re-elected. | nowrap | |- ! | James H. Morrison | | Democratic | 1942 | | Incumbent lost renomination.New member elected.Democratic hold. | nowrap | |- ! | Edwin Edwards | | Democratic | 1965 | Incumbent re-elected. | nowrap | |- ! | Speedy Long | | Democratic | 1964 | Incumbent re-elected. | nowrap | |} Maine |- ! | Stanley R. Tupper | | Republican | 1960 | | Incumbent retired.New member elected.Democratic gain. | nowrap | |- ! | William Hathaway | | Democratic | 1964 | Incumbent re-elected. | nowrap | |} Maryland Maryland redistricted its at-large district into an 8th district around Montgomery County, managing to adjust boundaries so no existing incumbents were displaced. |- ! | Rogers Morton | | Republican | 1962 | Incumbent re-elected. | nowrap | |- ! | Clarence Long | | Democratic | 1962 | Incumbent re-elected. | nowrap | |- ! | Edward Garmatz | | Democratic | 1947 | Incumbent re-elected. | nowrap | |- ! | George Hyde Fallon | | Democratic | 1944 | Incumbent re-elected. | nowrap | |- ! | Hervey Machen | | Democratic | 1964 | Incumbent re-elected. | nowrap | |- ! | Charles Mathias | | Republican | 1960 | Incumbent re-elected. | nowrap | |- ! | Samuel Friedel | | Democratic | 1952 | Incumbent re-elected. | nowrap | |- ! | Carlton R. Sickles | | Democratic | 1962 | | Incumbent retired to run for Governor of Maryland.New member elected.Republican gain. | nowrap | |} Massachusetts |- ! | Silvio O. Conte | | Republican | 1958 | Incumbent re-elected. | nowrap | |- ! | Edward Boland | | Democratic | 1952 | Incumbent re-elected. | nowrap | |- ! | Philip J. Philbin | | Democratic | 1942 | Incumbent re-elected. | nowrap | |- ! | Harold Donohue | | Democratic | 1946 | Incumbent re-elected. | nowrap | |- ! | F. Bradford Morse | | Republican | 1960 | Incumbent re-elected. | nowrap | |- ! | William H. Bates | | Republican | 1950 | Incumbent re-elected. | nowrap | |- ! | Torbert Macdonald | | Democratic | 1954 | Incumbent re-elected. | nowrap | |- ! | Tip O'Neill |