Kirkwood was elected to a full term in 1954, but lost a re-election bid in 1958 to Alan Cranston, who later became a United States Senator. Born in Mountain View, California, Kirkwood married Jean Hazard Gerlinger on August 30, 1933. In 1959, Kirkwood was appointed Utilities General Manager of the San Francisco Water Department.
He died in San Francisco in 1964.
The Water Department named a hydroelectric plant in Alpine County after Kirkwood, and the plant came online in 1967. Kirkwood"s son, Bob Kirkwood, was appointed by Governor Arnold Schwarzenegger to the Sierra Nevada Conservancy in 2005.