US Congressman. Born in La Crosse, Wisconsin, he grew up and attended school in Oregon, and from 1915 to 1917 attended the University of Oregon, where he was a member of Phi Delta Theta. On May 25, 1917, he enlisted in the United States Marine Corps. After basic training he was stationed at Fort Crockett in Galveston, Texas, serving from 1917 to 1918. He was discharged from the marines as an enlisted man on December 15, 1918, and commissioned a second lieutenant in the marine reserves on December 16, 1918. He remained a Reservist until 1946. Shortly after he was commissioned the Thompsons moved to Galveston. In 1919 he became treasurer of the American National Insurance Company. In 1920 he left that business to open a mercantile firm, Clark W. Thompson Company, which he owned until 1932. In 1927 he became involved in the Cedar Lawn Development Company; he served as its secretary-treasurer until 1934. He was appointed public relations counsel for the Moody interests in 1936. He organized the Fifteenth Battalion of the USMC Reserves in 1936. He was called up to national service in 1940, attended the Naval War College in 1941, and in 1942 was sent to the Southwestern Pacific Theater with his unit; he was the oldest officer in his theater. In 1943 he was returned to Washington, D.C., to become director of the marine reserves, a position he held until he retired as a colonel in 1946. He was awarded the Legion of Merit for his service. Thompson's concern with national defense led him into politics. In 1933 he was elected to represent the Seventh (later the Ninth) Texas Congressional District to fill the seat left vacant by the death of Clay Stone Briggs. He made a mark with his legislative efforts to strengthen the military before he was redistricted and chose to step down. He was elected in 1946 to the same seat, on the death of Joseph Jefferson Mansfield, and held it until he retired on January 3, 1967. In the Congress he was a member of the Agricultural, Maritime and Fisheries, and Ways and Means committees, playing an important role in bridging the gap between different factions of the state Democratic party. In 1968, after retiring from the House, he became legislative consultant for Hill and Knowlton and director of the Washington office of Tenneco. Thompson was a member of the Episcopal Church, president of the Galveston Chamber of Commerce in 1931 and 1935 to 1936 and a member of the American Legion, the Veterans of Foreign Wars, and the Texas State Society; he was also a thirty-second-degree Mason and a Shriner. He died in Galveston and was buried in Galveston Memorial Cemetery.