The 1918 United States Senate election in South Dakota took place on November 5, 1918. Incumbent Republican Senator Thomas Sterling sought re-election in his first popular election. He defeated former Governor Frank M. Byrne in the Republican primary and then faced former State Representative Orville Rinehart, the 1916 Democratic nominee for Governor, in the general election. Sterling defeated Rinehart, along with independent candidate W. T. Rafferty, by a wide margin to win re-election.
Democratic primary Candidates Orville V. Rinehart, former State Representative from Pennington County, 1916 Democratic nominee for Governor James Coffey, Internal Revenue Collector for North and South Dakota John E. Kelley, former U.S. Congressman from South Dakota's at-large congressional district
Results
Republican primary Candidates Thomas Sterling, incumbent U.S. Senator Frank M. Byrne, former Governor of South Dakota
Results
Socialist Primary Candidates John C. Knapp
Results
After winning the primary, Knapp withdrew as a candidate, citing his disagreement with the Socialist Party's anti-war policies.
General election Results
References