The 1968 United States Senate election in South Dakota took place on November 5, 1968. Incumbent Democratic Senator George McGovern ran for re-election to a second term. He was challenged by former Governor Archie M. Gubbrud, who was persuaded to enter the race by the South Dakota Republican establishment. McGovern defeated Gubbrud by a wide margin, even as Richard Nixon was defeating Hubert Humphrey in the state's presidential election in a landslide.
Both McGovern and Gubbrud were unopposed in their respective primaries. Gubbrud and incumbent Governor Nils Boe were seen as likely Republican candidates, but on March 22, Boe announced that he would not run. Shortly thereafter, a grassroots group of Republicans supportive of Gubbrud, named "Archie's Archers," started a campaign to persuade him to run, and received promises from other potential Republican candidates that they wouldn't run if Gubbrud did. On April 7, Gubbrud announced that he would run for the Senate, and subsequently received endorsements from prominent Republican figures, including former Vice-president Richard Nixon.