The 1912 South Dakota gubernatorial election was held on November 5, 1912. Incumbent Republican Governor
Robert S. Vessey declined to run for re-election to a third term. Lieutenant Governor
Frank M. Byrne won the Republican primary to succeed Vessey, and then faced State Senator
Edwin S. Johnson, the Democratic nominee, in the general election. Byrne only narrowly defeated Johnson, winning just 49% of the vote to Johnson's 46%, the closest gubernatorial election since
1898.