The 1942 United States Senate election in South Dakota took place on November 3, 1942. Incumbent Democratic Senator William J. Bulow ran for re-election to a third term. During the primary, Bulow was attacked for being insufficiently supportive of President Franklin Roosevelt's foreign policy and war preparedness. Former Governor Tom Berry, Bulow's chief opponent, drew a contrast between Bulow's isolationism and his support for Roosevelt's policies. In the end, Berry defeated Bulow in a landslide, and advanced to the general election, where he faced Harlan J. Bushfield, the incumbent Republican Governor of South Dakota. As Republicans gained ground nationwide, Bushfield defeated Berry in a landslide to pick up the seat for the Republican Party. Bushfield did not serve his full term, however; shortly before the 1948 U.S. Senate election, he died.