Democratic
South Dakota › South Dakota State Senate · November 3, 2026 · Updated Oct 16, 2026
South Dakota Legislative District 18
Nelson is very likely to win: Nelson wins in 49 of every 50 simulations.
Swihart (D)
2%
chance of winning
Nelson (R)
98%
- Average margin
- R+15.8
- 80% of outcomes
- R+25 to R+7
- Partisan lean
- R+27
- Polls
- No pollsmodel only
Nelson is very likely to win: Nelson wins in 49 of every 50 simulations.
Swihart (D)
3%
chance of winning
Nelson (R)
97%
- Average margin
- R+19.9
- 80% of outcomes
- R+33 to R+8
- Partisan lean
- R+27
- Polls
- No pollsmodel only
Range of outcomes
Final margin across our simulations; the white dashes mark the middle 80%.
The candidates
RepublicanIncumbent
Lauren Nelson
- Experience
- State legislature
What goes into the forecast
Every ingredient's estimate of the final margin.
- National environment
- D+9.5Election Day forecast
- South Dakota state offices
- +0.0Polls for governor, statewide and legislative races · details
- Environment here
- D+9.5Used by the fundamentals
- Swing reaching this office
- 58%Of a shift in the environment, from past legislative races since 2016
- Midwest adjustment
- +0.3How legislative races in the region have run against lean and environment lately
Each estimate is a margin before national and statewide uncertainty is simulated. Horizon blends polls, fundamentals and a little of the similar-places estimate, weighting each by how precise it is; Pulse uses polls and similar places only.
Fundamentals inputs
| Incumbency (+1 D, −1 R) | -1 |
| Fundraising edge (log ratio of individual money) | -0.67 |
| Elected-experience edge | -0.67 |
| First-term incumbent | 0 |
| Seat's last result vs. expectation | 15.03 |
| Incumbent's last result vs. expectation | 15.03 |
Polls
No public polls of this race. The forecast relies on fundamentals and on polling of similar places in the state.
The district
Lean R+27: how much more Democratic or Republican than the nation it votes for president.
Presidential vote
Precinct results re-aggregated to the current district lines.
Who lives here
- Population
- 23,414
- People per km²
- 15
- Adults with a B.A.+
- 31%
- White, no degree
- 59%of adults
- White 87%
- Hispanic 6%
- Black 2%
- Other / multiracial 5%
American Community Survey 2020–2024, aggregated from census tracts.
Past results
Results in the same-numbered district; earlier elections may have used different lines.
2024
10,818 votes · R+14.4✓ Lauren Nelson (R)57.2%
Sarah Carda (D)42.8%
2024 President Vote in this district
372 two-party votes · R+36.0 · R+34.5 vs. the nation✓ Donald Trump (R)68.0%
Kamala Harris (D)32.0%
2022
8,839 votes · R+30.1✓ Jean M Hunhoff (R)65.0%
Fredrick Bender (D)35.0%
2020 Earlier district lines
10,597 votes · R+19.7✓ Jean Hunhoff (R)59.8%
Jordan Foos (D)40.2%
2020 President Vote in this district
11,365 two-party votes · R+24.6 · R+29.1 vs. the nation✓ Donald Trump (R)62.3%
Joe Biden (D)37.7%
2016 President Vote in this district
9,654 two-party votes · R+25.7 · R+27.9 vs. the nation✓ Donald Trump (R)62.8%
Hillary Clinton (D)37.2%