McIntyre was born on a farm in Dewey County, Oklahoma, attended grade schools at Ramona, Oklahoma, and graduated from the high school at Tulsa, and from the law department of the University of Colorado at Boulder in 1928.

He was an associate attorney in the solicitor's office of the United States Department of Agriculture in Washington, 1938.

He was deputy attorney general of Wyoming in 1943 and 1944, and served as a staff sergeant in Headquarters Battery, Six Hundred and Sixtieth Field Artillery, from February 9, 1944, to August 22, 1945; he was decorated with the French Croix de Guerre.

He was State auditor for Wyoming in 1946, and was an unsuccessful candidate for election in 1946 to the 80th Congress.

He was Democratic nominee for Governor in 1950, and was elected in 1960 as a justice of the Wyoming Supreme Court for a four-year term; he was reelected in 1964 and served continuously until his death, November 30, 1974, in Cheyenne.