This Presidential Primary coincides with a state/local primary. These coinciding primaries tend to have an impact upon voter turnout.

Since there is only one candidate, the primary is cancelled.

Tuesday 2 June 2020 (presumably): South Dakota Primary. Hours reportedly 7:00a-7:00p CDT (1200-0000 UTC) / 7:00a-7:00p MDT (1300-0100 UTC). Delegate Selection: Winner-Take-All Primary. Voter Eligibility: Closed Primary.

Primary (preliminary)
Included in Nationwide vote.

All 29 of South Dakota's delegates to the Republican National Convention are allocated to the presidential contender who receives the most votes in today's South Dakota Presidential Primary. [Bylaws of the South Dakota Republican Party, SECTION VI. 1.]

In addition, 3 party leaders, the National Committeeman, the National Committeewoman, and the chairman of the South Dakota's Republican Party, will attend the convention as bound delegates by virtue of their position.

[Delegates] ... will ... vote for that candidate through the first ballot at the National Convention unless that candidate withdraws, suspends campaign activities, or fails to have his or her name placed in nomination at the National Convention. [SECTION VI. 2.]

Thursday 18 June - Saturday 20 June 2020: State Convention in Watertown. All Republicans registered to vote in South Dakota may apply to become a National Convention delegate by submitting an application to the party by 1 May 2020.