The 2010 United States Senate election in South Dakota was held on November 2, 2010, along other elections to the United States Senate in other states as well as elections to the United States House of Representatives and various state and local elections. Incumbent Republican Senator John Thune won re-election to a second term unopposed.
Thune was narrowly elected to his first term over Democratic Senate Minority Leader Tom Daschle with 51% of the vote in 2004. Despite his lack of seniority, Thune became chairman of the U.S. Republican Policy Committee in 2009.
Thune did not face any opposition whatsoever in his 2010 re-election. He won 100% of the votes cast in this senate race, just like John C. Stennis in the 1958 Mississippi senate race. South Dakota State Senate Minority Leader Scott Heidepriem said "We just concluded that John Thune is an extremely popular senator who is going to win another term in the Senate." There were exactly 89,136 undervotes compared to the concurrent gubernatorial election.
Source
Counties that flipped from Democratic to Republican
Official campaign websites (archived)