He graduated from the law department of the University of Nebraska at Lincoln in 1904, was admitted to the bar and commenced practice in Livingston, Montana in 1905.

O'Connor was narrowly re-elected in 1938 over W. C. Husband when Republicans nationwide gained eighty-one House seats.

O'Connor was an isolationist during the buildup to World War II, and he voted against providing aid to Britain in 1941.

[2] O'Connor served as the Chairman of the House Committee on Indian Affairs during the 78th United States Congress, from 1943 to 1945.

This article incorporates public domain material from the Biographical Directory of the United States Congress