A blacksmith before entering politics, he was a Teachta Dála (Territorial Decoration) for over twenty years, and served three times as Mayor of Galway. He was re-elected five times until his defeat at the 1977 general election by his party colleague John Mannion.
A long-serving member of both Galway County Council and Galway City Council, Coogan served as mayor of Galway city from 1961 to 1962, 1969 to 1970 and 1974 to 1975.