1900 United States presidential election in South Dakota

The 1900 United States presidential election in South Dakota took place on November 6, 1900. All contemporary 45 states were part of the 1900 United States presidential election. State voters chose four electors to the Electoral College, which selected the president and vice president.

South Dakota was won by the Republican nominees, incumbent President William McKinley of Ohio and his running mate Theodore Roosevelt of New York. They defeated the Democratic nominees, former U.S. Representative and 1896 Democratic presidential nominee William Jennings Bryan and his running mate, former Vice President Adlai Stevenson I. McKinley won the state by a margin of 15.59% in this rematch of the 1896 presidential election. The return of economic prosperity and recent victory in the Spanish–American War helped McKinley to score a decisive victory.

McKinley had previously lost the state to Bryan four years earlier, who in turn would lose the state to William Howard Taft in 1908.