State
(class)
Vacator Reason for change Successor Date of successor's
formal installation
New Hampshire
(3)
Vacant Disputed election. Norris Cotton appointed to seat until special election resolved dispute. Norris Cotton
(R)
August 8, 1975
New Hampshire
(3)
Norris Cotton
(R)
Successor elected September 18, 1975 John A. Durkin
(D)
September 18, 1975
Michigan
(1)
Philip Hart
(D)
Died December 26, 1976 Donald W. Riegle, Jr.
(D)
December 27, 1976
Missouri
(1)
Stuart Symington
(D)
Resigned December 27, 1976 John Danforth
(R)
December 27, 1976
Nebraska
(1)
Roman Hruska
(R)
Resigned December 27, 1976 Edward Zorinsky
(D)
December 28, 1976
Ohio
(1)
Robert Taft, Jr.
(R)
Resigned December 28, 1976 Vacant Not filled this term
Rhode Island
(1)
John O. Pastore
(D)
Resigned December 28, 1976 John Chafee
(R)
December 29, 1976
Minnesota
(2)
Walter Mondale
(DFL)
Resigned December 30, 1976 after being elected Vice-President of the United States. Wendell Anderson
(DFL)
December 30, 1976
California
(1)
John V. Tunney
(D)
Resigned January 1, 1977 S. I. Hayakawa
(R)
January 2, 1977