In the winter of 1939 he was a visiting lecturer in American Literature at Pomona College.
[1] In 1945 he became professor at the University of Illinois, where he spent the remainder of his career, retiring in 1972.
Nevertheless, he decided this would be a focus of his teaching, and his professional growth thus paralleled the emergence of the discipline.
He also did not expect that he would become one of the foremost experts in literature of the trans-Appalachian west (now known as the Midwest, but in the hey day of its settlement by Euro-Americans known as "the West"), yet he became that and published copiously both in journals and in books on a wide range of related subjects.
[4] After Flanagan formally retired he remained active in his organizational roles and as a writer well into his 80s.