Born in
Youngstown, Ohio, Callahan graduated from Ursuline High School in 1946. He went on to play college football at
Marquette University in
Milwaukee, Wisconsin, where he received a bachelor's degree in mathematics in 1951 and a master's degree in educational administration in 1952. From 1970 - 1975, Callahan was principal of
Boylan Catholic High School, and in 1971 he became the first superintendent of the Rockford Area Catholic Schools. Prior to this, Callahan served a variety of positions at Boylan, including the first athletic director, first head coach in football, basketball, and chair of the mathematics department. In 1975, Callahan became the Assistant Secretary of State for Illinois under Secretary
Michael Howlett. Immediately prior to his presidential appointment, Callahan served as director of the Illinois Department of Financial Institutions under Governor
James R. Thompson. As director, he was responsible for the supervision of 2,000 consumer finance companies, 1,200 currency exchanges, and 1,000 Illinois-chartered credit unions. ==Chairman of the NCUA==