After the war, Gilligan returned to Cincinnati to teach literature at Xavier University from 1948 to 1953. He also served as member of the Cincinnati city council from 1953 to 1963, and was a candidate for Ohio Congressman-at-Large in 1962. In 1964 he was elected to the Eighty-ninth Congress as a representative for Ohio's 1st district, serving from January 3, 1965 – January 3, 1967. Gilligan narrowly lost his re-election bid to the Ninetieth Congress in 1966 to Republican Robert Taft Jr. after the Republican-controlled Ohio General Assembly redrew his district to favor the Republican Party. In 1968, Gilligan defeated sitting U.S. Senator Frank J. Lausche in the Democratic primary; however, he narrowly lost in the general election to Republican William B. Saxbe after Lausche refused to support him in the general election. Gilligan won the election for the Governorship of Ohio in 1970, defeating Republican state AuditorRoger Cloud, and serving from 1971 to 1975. His signature achievement in office was the creation of Ohio's state income tax. Gilligan lost reelection in the strongly Democratic Watergate year of 1974 to former Republican governor James A. Rhodes by only 11,488 votes out of 3,072,010 cast. The backlash of big business against Gilligan and in favor of Rhodes was seen by many as the reason for his defeat. Gilligan subsequently served as the administrator of the United States Agency for International Development from 1977 to 1979. In 1980, he was elected to the Common Cause National Governing Board. He served as director of the Institute for Public Policy from 1979 to 1986, and taught at the University of Notre Dame from 1986 to 1992. He also served as director of the civic issues forum at the University of Cincinnati School of Law. In 1999, Gilligan was elected to the Board of Education of the Cincinnati Public Schools. He chose not to stand for re-election when his term expired in 2007.
Family
Gilligan was the father of four children, including Kathleen Sebelius, who served as Governor of Kansas and United States Secretary of Health and Human Services. They became the first father/daughter governor duo in the United States after her election.
Death
Gilligan died at home in Cincinnati on August 26, 2013 at the age of 92. His son said he died of congestive heart failure.
On October 17, 1973, Gilligan, while governor, claimed to have seen a UFO while driving near Ann Arbor, Michigan. During a press conference he stated: "I saw one the other night, so help me. I'm absolutely serious. I saw this."
Legacy
The Gilligan Complex at the Ohio Expo Center and State Fair in Columbus, Ohio, is named in honor of Gilligan.