John McDuffie (September 25, 1883 - November 1, 1950) was born in River Ridge, Alabama in Monroe County on September 25, 1883. He was educated by private tutors. He attended college at Southern University in Greensboro. He later attended Alabama Polytechnic Institute in Auburn, Alabama, where he in graduated in 1904. McDuffie went to Law School in University of Alabama at Tuscaloosa and graduated there in 1908. He was admitted to Bar the same year.
He was elected to the Alabama State House of Representatives in 1907 and served until 1911. He later became a Prosecutor for the First Judicial Circuit Court of Alabama and served there until 1919.
He was elected to the United States House of Representatives in 1918, and served from March 4, 1919 until his resignation on March 2, 1935. During his tenure in the House he served as Minority Whip for 71st Congress, and later as Majority Whip for 72nd Congress. He also served as Chairman for Committee on Insular Affairs in 73rd Congress and 74th Congress
In 1935, President Franklin Delano Roosevelt appointed McDuffie to a seat on the U.S. District Court for the Southern District of Alabama. He served on that court until his death in Mobile, Alabama on November 1, 1950. He is interred in Pine Crest Cemetery.