The closest gubernatorial election in South Dakota history was won by Populist Andrew E. Lee in 1896. Lee was a prosperous merchant and the mayor of Vermillion. He ran on a “fusion ticket,” supported by the Democratic and Populist parties, and defeated Republican A. O. Ringsrud by 315 votes, or 0.4% – both the closest margins in South Dakota history. Ringsrud was the secretary of state and, like Lee, had been born in Norway. In 1898, Lee was reelected by the second-closest margins in state history: 370 votes, or 0.5%, over Republican challenger Kirk G. Phillips, the state treasurer.
South Dakota Republicans have won ten straight gubernatorial elections from 1978 to 2014, controlling the governor’s office for forty years. During that time, the closest gubernatorial election was 1986, when George S. Mickelson defeated R. Lars Herseth by 10,645 votes, or 3.6%. This modern era also includes two of the three biggest wins in state history: Dennis Daugaard’s 45.0% win over Susan Wismer in 2014, and Bill Janklow’s 41.7% margin over Mike O’Connor in 1982.
The late 1950s and early 1960s also featured several competitive elections for governor. In 1958, Ralph Herseth ended twenty-two years of Republican control of the governor’s office, winning an open seat against Republican Phil Sanders by 2.8%. Two years later, Republican House Speaker Archie Gubbrud unseated Herseth by 1.5% in an upset that was the third-closest election in SD history, following only Governor Lee’s two victories. Gubbrud was comfortably reelected in 1962, but in 1964, Republican Nils Boe won the governor’s office by only 3.3% over Democrat John Lindley, who had been Herseth’s lieutenant governor.
Below is a list of winning candidates for Governor of South Dakota, ranked by the winner’s percentage margin over the runner-up. Listed “major opponents” are those who won at least 10% of the vote.
| Year | Winning candidate | Margin | Major opponents |
| 1896 | Andrew E. Lee (POP) | 0.4% | Amund O. Ringsrud (REP) |
| 1898 | Andrew E. Lee (POP) | 0.5% | Kirk G. Phillips (REP) |
| 1960 | Archie Gubbrud (REP) | 1.5% | Ralph Herseth (DEM) |
| 1912 | Frank M. Byrne (REP) | 2.8% | Edwin S. Johnson (DEM) |
| 1958 | Ralph Herseth (DEM) | 2.8% | Phil Saunders (REP) |
| 1936 | Leslie Jensen (REP) | 3.2% | Tom Berry (DEM) |
| 1964 | Nils Boe (REP) | 3.3% | John Lindley (DEM) |
| 1986 | George S. Mickelson (REP) | 3.6% | R. Lars Herseth (DEM) |
| 1928 | W. J. Bulow (DEM) | 5.5% | Buell F. Jones (REP) |
| 1930 | Warren E. Green (REP) | 6.7% | David A. McCullough (DEM) |
| 1926 | W. J. Bulow (DEM) | 7.1% | Carl Gunderson (REP) |
| 1974 | Richard F. Kneip (DEM) | 7.2% | John E. Olson (REP) |
| 1938 | Harlan J. Bushfield (REP) | 7.9% | Oscar Fosheim (DEM) |
| 1956 | Joe Foss (REP) | 8.8% | Ralph Herseth (DEM) |
| 1970 | Richard F. Kneip (DEM) | 9.7% | Frank Farrar (REP) |
| 1940 | Harlan J. Bushfield (REP) | 10.3% | Lewis W. Bicknell (DEM) |
| 1962 | Archie Gubbrud (REP) | 12.2% | Ralph Herseth (DEM) |
| 1890 | Arthur C. Mellette (REP) | 12.8% | H. L. Loucks (IND), Maris Taylor (DEM) |
| 1932 | Tom Berry (DEM) | 13.2% | Warren E. Green (REP) |
| 1954 | Joe Foss (REP) | 13.3% | Ed C. Martin (DEM) |
| 1978 | William J. Janklow (REP) | 13.3% | Roger McKellips (DEM) |
| 1900 | Charles N. Herreid (REP) | 14.4% | Burre H. Lien (POP) |
| 1994 | William J. Janklow (REP) | 14.8% | James Beddow (DEM) |
| 2002 | M. Michael Rounds (REP) | 14.8% | James W. Abbott (DEM) |
| 1914 | Frank M. Byrne (REP) | 14.9% | James W. McCarter (DEM) |
| 1968 | Frank Farrar (REP) | 15.3% | Robert Chamberlin (DEM) |
| 1966 | Nils Boe (REP) | 15.4% | Robert Chamberlin (DEM) |
| 1892 | Charles H. Sheldon (REP) | 15.5% | Abraham L. Van Osdel (IND), Peter Couchman (DEM) |
| 1908 | Robert S. Vessey (REP) | 15.9% | Andrew E. Lee (DEM) |
| 1922 | William H. McMaster (REP) | 16.3% | Louis Napoleon Crill (DEM), Alice Lorraine Daly (NPL) |
| 1916 | Peter Norbeck (REP) | 17.3% | Orville V. Rinehart (DEM) |
| 1990 | George S. Mickelson (REP) | 17.8% | Robert L. Samuelson (DEM) |
| 1934 | Tom Berry (DEM) | 17.9% | William C. Allen (REP) |
| 1894 | Charles H. Sheldon (REP) | 18.0% | Isaac Howe (IND), James A. Ward (DEM) |
| 1972 | Richard F. Kneip (DEM) | 20.1% | Carv Thompson (REP) |
| 1950 | Sigurd Anderson (REP) | 21.8% | Joe Robbie (DEM) |
| 1948 | George T. Mickelson (REP) | 22.2% | Harold J. Volz (DEM) |
| 1910 | Robert S. Vessey (REP) | 22.5% | Chauncey L. Wood (DEM) |
| 1942 | M. Q. Sharpe (REP) | 23.0% | Lewis W. Bicknell (DEM) |
| 2010 | Dennis Daugaard (REP) | 23.0% | Scott Heidepriem (REP) |
| 2006 | M. Michael Rounds (REP) | 25.6% | Jack Billion (DEM) |
| 1918 | Peter Norbeck (REP) | 27.1% | Mark P. Bates (IND), James E. Bird (DEM) |
| 1920 | William H. McMaster (REP) | 30.0% | Mark P. Bates (NPL), William W. Howes (DEM) |
| 1924 | Carl Gunderson (REP) | 31.0% | W. J. Bulow (DEM) |
| 1944 | M. Q. Sharpe (REP) | 31.0% | Lynn Fellows (DEM) |
| 1998 | William J. Janklow (REP) | 31.2% | Bernie Hunhoff (DEM) |
| 1946 | George T. Mickelson (REP) | 34.3% | Richard Haeder (DEM) |
| 1902 | Charles N. Herreid (REP) | 36.0% | John W. Martin (DEM) |
| 1906 | Coe I. Crawford (REP) | 38.6% | John A. Stransky (DEM) |
| 1889 | Arthur C. Mellette (REP) | 38.7% | P. F. McClure (DEM) |
| 1952 | Sigurd Anderson (REP) | 40.3% | Sherman Iverson (DEM) |
| 1982 | William J. Janklow (REP) | 41.7% | Michael O’Connor (DEM) |
| 1904 | Samuel H. Elrod (REP) | 43.6% | Louis Napoleon Crill (DEM) |
| 2014 | Dennis Daugaard (REP) | 45.0% | Susan Wismer (REP) |
Abbreviations for parties are REPublican, DEMocratic, INDependent, POPulist (these candidates ran on a Democratic/Populist fusion ticket), and NPL for Nonpartisan League.
In 1890, 1892, and 1894, IND refers to the “Independent Party” which was a precursor to the Populists. In 1918, IND refers to the independent candidate was associated with the Nonpartisan League, which gained ballot status as a political party in 1920 and 1922.
