99chambers

South Dakota House of Representatives seat · lines in effect since 2022

South Dakota Legislative District 18

A district of about 23,000 people, 31% of adults with a bachelor's degree. It votes R+33.2 relative to the nation for president.

Julie Auch (R) · since Nov 8, 2022Mike Stevens (R) · since Nov 6, 2012Next election Nov 7, 2028The 2026 race →

Where it sits among all 34 seats

Every South Dakota House of Representatives seat by partisan lean, from most Democratic to most Republican. Lean is the seat's presidential vote on current lines, relative to the nation.

R+33.217th most
Democratic
Most DemocraticMost Republican18th seat · the majority lineDistrict 18

Source: 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET

Every race on these lines

Results recomputed from precinct returns as if today's boundaries had always existed, so years compare like for like.

202220242026
South Dakota House of RepresentativesR+1.7R+19.8R+12.1

Outlined: the race for this seat itselfBlank: no race that year

Source: 99chambers results archive: precinct results allocated to current lines; 2026: South Dakota Secretary of StateUpdated Nov 7, 2026, 3:01 PM ET

Who lives here, compared

Grey bars show the spread of all 34 seats. Small marks are other seats in South Dakota. The black marker is District 18.

Adults with a bachelor's degree31% 58th pct · 15th of 34 in SD

Higher than 58% of seats.

White adults without a degree59% 64th pct · 13th of 34 in SD

Higher than 64% of seats.

Hispanic residents6% 79th pct · 8th of 34 in SD

Higher than 79% of seats.

Black residents2% 61st pct · 14th of 34 in SD

Higher than 61% of seats.

Asian residents0% 9th pct · 31st of 34 in SD

Lower than 91% of seats.

People per square mile39 55th pct · 16th of 34 in SD

Denser than 55% of seats.

Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current linesUpdated Oct 13, 2026, 5:06 AM ET

Seats most like this one

Nearest seats on demographics, density and lean.

District 8
30% college gradsR+36.2Held RDistrict 25
33% college gradsR+38.6Held RDistrict 1
26% college gradsR+22.3Held RDistrict 20
22% college gradsR+41.2Held R

Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current lines; 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET

Who has held it

These lines took effect in 2022.

  1. John R. Marquardt (R)
    2027– · Won 2026 by 12.1
  2. Mike Stevens (R)
    2023– · Won 2022 by 7.4, 2024 by 25.3, 2026 by 25.7
  3. Julie Auch (R)
    2023–2027 · Won 2022 by 1.7, 2024 by 19.8

Source: Past results: 99chambers results archive (MEDSL, Klarner, state election offices)