- Lead
- 135,316
- Total
- 187,395
- vs nation
- D+73.7
California 18th State House District
President margin by year
Place winner margin
President results by year
Modeled candidate-vote estimate on current district boundaries
- Lead
- 176,851
- Total
- 220,121
- vs nation
- D+75.9
- Lead
- 152,939
- Total
- 194,239
- vs nation
- D+77.9
- Lead
- 139,344
- Total
- 172,205
- vs nation
- D+77.1
- Lead
- 143,897
- Total
- 178,704
- vs nation
- D+73.3
- Lead
- 121,106
- Total
- 156,696
- vs nation
- D+79.7
- Lead
- 96,417
- Total
- 136,375
- vs nation
- D+70.2
- Lead
- 83,547
- Total
- 127,582
- vs nation
- D+58.5
Key facts
- 2024 presidential margin
- D+72.2MIT Election Lab
- Population
- 483,9632024 5-year
- Population density
- 7,086 / sq mi2024 5-year · TIGER/Line
- Land area
- 68.3 sq miTIGER/Line
- Median household income
- $100,6762024 5-year
- White (non-Hispanic)
- 26.3%2024 5-year
- Black
- 19.4%2024 5-year
- Hispanic / Latino
- 27.6%2024 5-year
- Peak Democratic margin
- D+80.9 in 2012MIT Election Lab
- Peak Republican margin
- R+30.6 in 1924MIT Election Lab
- Most similar
- Assembly District 14, CA · twin score 98.6
presidential history
Party record book
California 18th State House District · the strongest Democratic and Republican presidential performances recorded here, measured three ways.
1892–2024 (partial returns from 1876) · 38 presidential cycles · 38 with a vote-share denominator · 34 with a national benchmark
Highest vote share
Largest share of the presidential candidate vote cast here.
Democratic
Joe Biden2020
89.1%
196,128 votes · D+80.3 · modeled estimate
Runner-up · Barack Obama, 2008 · 89.1%
Republican
Theodore Roosevelt1904
50.1%
2,555 votes · R+21.7 · modeled estimate
Runner-up · Warren G. Harding, 1920 · 48.4%
Most votes
Largest number of votes cast for the party’s presidential nominee here.
Democratic
Joe Biden2020
196,128votes
89.1% of the vote · D+80.3 · modeled estimate
Runner-up · Hillary Clinton, 2016 · 167,505 votes
Republican
Richard Nixon1972
25,466votes
22.6% of the vote · D+52.2 · modeled estimate
Runner-up · Dwight D. Eisenhower, 1956 · 24,401 votes
Best relative to the U.S.
This Place’s margin against the national margin in the same election — positive when it leaned toward the party more than the country did.
Democratic
John Kerry2004
+79.7pts D vs U.S.
Place D+77.3 · U.S. R+2.5 · modeled estimate
Runner-up · Hillary Clinton, 2016 · +77.9 pts
Republican
Calvin Coolidge1924
+5.4pts R vs U.S.
Place R+30.6 · U.S. R+25.2 · a third-party candidate carried the Place · modeled estimate
Runner-up · Theodore Roosevelt, 1904 · +2.1 pts
Current officeholders
State legislative officeholder from OpenStates nightly current-legislator data.
Senate and governor results are in the Office selector at the top of this page.
U.S. House
Each row is a county-allocated estimate of U.S. House votes for this district — county returns apportioned onto its boundary, not precinct-counted. “Vote lead” is the estimated local lead here, not necessarily the winner of the full contest.
With a 2024 presidential margin exceeding 72 points Democratic, AD-18 ranks among the most heavily one-sided state house districts in the country, reflecting dense urban concentration and a electorate with exceptionally low two-party competition.
Across the recorded series it reached a Democratic high of 80.9 points in 2012 and a Republican high of 30.6 points in 1924. Between 2020 and 2024 the district moved 8.1 points toward the Republican candidate; the 2024 margin was 72.2 points.
A population of 483,963, a 26% non-Hispanic-white share, and a median household income of $100,676 describe the district. The district's voting pattern over the last decade is most similar to that of Assembly District 14 and Assembly District 55.
The state-house districts whose fingerprint — 2000–2024 trajectory, demographics, ancestry, religion — sits closest to this one, and why.
Twin score (0–100) = weighted cosine between tier-standardized fingerprints: presidential margins 2000–2024 with 12-yr trend and elasticity, ACS income, age, education, population and race, top reported ancestries, and religious adherence — chips name the closest-shared dimensions and the widest gap. Re-weight the groups in the twins explorer.
District research tools
Open the source-auditable district brief for electoral baseline, electorate, current-cycle coverage, geography, official dates, and methodology. Open campaign intelligence report → · Browse all comparisons →
California 18th State House District. Akashic. https://akashic.app/sld-lower/06018/. Accessed May 20, 2026. License: CC BY 4.0.