Ballot initiative mechanics in South Dakota
How ballot initiatives work covers the four mechanisms nationally. This page covers South Dakota's specific numbers and deadlines. South Dakota was the first state in the country to adopt the ballot initiative process, in 1898, and still offers initiated statutes, initiated constitutional amendments, and referred laws.
South Dakota's process
Every signature threshold is calculated as a percentage of total votes cast for governor in the most recent gubernatorial election, so the required number changes each cycle based on turnout. Both initiated constitutional amendments and initiated statutes must meet a single-subject rule, added for amendments by voters in 2018's Amendment Z with a companion law extending it to statutes. The rule has teeth: the 2020 marijuana legalization measure was struck down by the state Supreme Court for covering more than one subject. A 2025 law now has the Secretary of State review measures for single-subject compliance before circulation, with a denial appealable to the state Supreme Court within 15 days.
South Dakota has no geographic distribution requirement. Signatures are counted statewide regardless of county. A 2025 bill would have required signatures from all 35 state Senate districts for constitutional amendments, but Governor Rhoden vetoed it and the legislature sustained the veto.
Deadlines and numbers
- Initiated measure: 5% of last gubernatorial vote, currently 17,508 signatures
- Constitutional amendment: 10% of last gubernatorial vote, currently 35,017 signatures
- Referred law: 5% of last gubernatorial vote, currently 17,508 signatures
- Circulation window: cannot start more than 24 months before the general election
- Statutory filing deadline: first Tuesday in May before the election, though this is currently contested (see gap below)
- Geographic distribution requirement: none
Where to go
- Secretary of State, Ballot Question Information: sdsos.gov/elections-voting/upcoming-elections/ballot-question-information
Rules
South Dakota's process is old and, on paper, straightforward: a statewide signature percentage tied to the last governor's race, no county-by-county distribution requirement, and three separate tracks depending on whether you're proposing a statute, a constitutional amendment, or challenging a law the legislature just passed. The single-subject rule is the one place this state has real enforcement teeth, having already struck down a high-profile 2020 measure in court, and a 2025 law now front-loads that review to before circulation even starts.
The filing deadline itself is genuinely unsettled right now. A 2025 law, HB 1184, tried to move the deadline earlier, to February in election years. A federal judge blocked that change as unconstitutional and denied the state's request to stay the ruling, but the dispute was still being litigated as of mid-2026. Anyone planning a South Dakota petition drive needs to check the current, live deadline with the Secretary of State's office rather than assume either the old May deadline or the blocked February one applies, since this is an open legal question, not a settled fact.
A second gap: no confirmed filing fee for initiative or referendum petitions was found. Available sources address only candidate filing fees. Confirm both the fee question and the current deadline directly before starting a signature drive. For anything South Dakota-specific this page doesn't answer, route to /engage.