O.M. was born March 22, 1917 in Chillicothe, Texas, to Ewing Bryan and Myrtice Brock Calhoun. He graduated from Chillicothe High School in 1935 and went to work in Dallas. He served in the Air Force during WWII. He passed the bar exam and received his law license in November 1947. He graduated from the University of Texas Law School in January 1948 and began his law practice in Amarillo on February 8, 1948. He was in private practice for several months before joining the county attorney’s office. He returned to private practice as Folley, Snodgrass & Calhoun in 1951.
O.M. held numerous offices over his law career, including president of the Amarillo Bar Association. He was a member of the Phi Alpha Delta law fraternity. In 1962, he was named the Chairman of the Panhandle Chapter of the National Multiple Sclerosis Society. He ran for district judge in 1974, but soon realized that politics was not his forte. He served as chairman of the Potter-Randall County Child Welfare Board.
He was Resident of Counsel for the Hinkle, Cox, Eaton, Coffield & Hensley law firm, covering the entire Texas panhandle. He primarily served as general counsel for Southwestern Public Service Company and United New Mexico Bank of Roswell.
He was a charter member of St. Paul United Methodist Church, and was also a member of the church’s administrative board.
He was preceded in death by his wife Elizabeth Mae Calhoun; his wife Lola Calhoun; one brother, two sisters and his grandson, Chad Barkley.
He is survived by his wife Louise; his daughters Cathy Barkley and husband Danny; Marsha Singer and husband Bill; his son Bryan Calhoun and wife Joyce; his brother Jack Calhoun of Houston; four grandchildren and three great-grandchildren.