| Election Name: | 1890 South Dakota gubernatorial election |
| Country: | South Dakota |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1889 South Dakota gubernatorial election |
| Previous Year: | 1889 |
| Next Election: | 1892 South Dakota gubernatorial election |
| Next Year: | 1892 |
| Election Date: | November 4, 1890 |
| Image1: | File:Governor Arthur C Mellette.jpg |
| Nominee1: | Arthur C. Mellette |
| Party1: | Republican Party (United States) |
| Popular Vote1: | 34,487 |
| Percentage1: | 44.46% |
| Nominee2: | Henry Loucks |
| Party2: | Independent Party |
| Popular Vote2: | 24,591 |
| Percentage2: | 31.70% |
| Nominee3: | Maris Taylor |
| Party3: | Democratic Party (United States) |
| Popular Vote3: | 18,484 |
| Percentage3: | 23.83% |
| Map Size: | 250px |
| Governor of South Dakota | |
| Before Election: | Arthur C. Mellette |
| Before Party: | Republican Party (United States) |
| After Election: | Arthur C. Mellette |
| After Party: | Republican Party (United States) |
The 1890 South Dakota gubernatorial election was held on November 4, 1890. Incumbent Republican Governor Arthur C. Mellette ran for re-election to a second term. He was challenged in the general election by State Surveyor General Maris Taylor, the Democratic nominee, and Henry A. Loucks, the President of the South Dakota Farmers' Alliance and the Independent Party nominee. In part because the left-leaning vote was split, Mellette won re-election, but by a significantly reduced margin, winning a weak plurality with just 44% of the vote. Loucks beat out Maris for second place, receiving 32% of the vote to Taylor's 24%.
At the Democratic convention in June 1890, many convention delegates wanted to nominate Bartlett Tripp, the former Chief Justice of the Dakota Territorial Supreme Court. However, Tripp had declined to be a candidate several weeks prior, and State Surveyor General Maris Taylor was nominated by acclamation.[1] Similarly, at the Republican convention in August, Governor Arthur C. Mellette received the gubernatorial nomination by acclamation.[2]
Separately, the South Dakota Farmers' Alliance held a convention in 1890 and delegates voted to form the Independent Party and to contest the state elections.[3] When the delegates reconvened at their nominating convention in July, Henry L. Loucks, the President of the Alliance, who had been seen as the frontrunner for the Independent Party's nomination in June, faced a challenge from Abraham Lincoln Van Osdel,[3] a former territorial legislator.[4] A close race developed between Loucks and Van Osdel, with just two votes separating them on the first, informal ballot and Loucks leading, 127–125. On the second, formal ballot, Loucks defeated Van Osdel by a wider margin, 134–115, and Van Osdel was subsequently nominated for Lieutenant Governor.[3]