Corning's father was one of the leaders of the Democratic Party organization formed by Daniel P. O'Connell, which wrested control of Albany city and county from the Republican organization led by William Barnes Jr. in the early 1920s. The O'Connell machine proved so durable that it still largely controlled Albany County until the early 1980s, one of the last such organizations to remain viable. Corning entered politics at an early age as an affiliate of the O'Connell organization, winning a seat in the New York State Assembly in 1935. After serving in the Assembly during the 1936 legislative session, Corning won election to the New York State Senate, where he served from 1937 to 1941. Corning was elected mayor in 1941. He continued to win election every four years until 1981, and served from 1941 until his death in 1983. Corning was drafted for World War II and served in the United States Army's 2nd Infantry Division during combat in Europe. In 1946, he was the Democratic Party's unsuccessful nominee for lieutenant governor. In the 1970s Corning teamed with Governor Nelson A. Rockefeller to finance construction of the Empire State Plaza, a large state government office complex near Albany's downtown area. The plaza's tallest building, Erastus Corning Tower, was named in Corning's honor.