Columns: State (class) | Vacator | Reason for change | Successor | Date of successors formal installation
Hawaii (1) | New seats | Hawaii achieved statehood August 21, 1959. | Hiram Fong (R) | August 21, 1959 | Hawaii (3) | New seats | Hawaii achieved statehood August 21, 1959. | Oren E. Long (D) | August 21, 1959 | North Dakota (1) | William Langer (R) | Died November 8, 1959 | Clarence N. Brunsdale (R) | November 19, 1959 | Oregon (2) | Richard L. Neuberger (D) | Died March 9, 1960 | Hall S. Lusk (D) | March 16, 1960 | North Dakota (1) | Clarence N. Brunsdale (R) | Successor elected August 7, 1960. | Quentin N. Burdick (D) | August 8, 1960 | Missouri (3) | Thomas C. Hennings, Jr. (D) | Died September 13, 1960 | Edward V. Long (D) | September 23, 1960