Data as of October 18, 2026 · refreshed automatically from the official California voter file
San Luis Obispo County, CA has 183,260 active registered voters — 34.5% Republican, 38.3% Democratic, and 18.5% with no party affiliation, as of October 2026.
Party registration
Most reliable-voting precincts
| # | Precinct | Active voters | Supervoters | Supervoter % |
|---|---|---|---|---|
| 1 | 2090011 | 454 | 391 | 86.12% |
| 2 | 4790022 | 581 | 496 | 85.37% |
| 3 | 4790027 | 1,153 | 982 | 85.17% |
| 4 | 4790018-C | 420 | 356 | 84.76% |
| 5 | 3090005-B | 759 | 615 | 81.03% |
| 6 | 2090049 | 546 | 439 | 80.4% |
| 7 | 3070009-B | 569 | 455 | 79.96% |
| 8 | 4790012-B | 899 | 718 | 79.87% |
| 9 | 4790014-B | 711 | 563 | 79.18% |
| 10 | 4011004 | 414 | 324 | 78.26% |
Supervoters are active registered voters who cast a ballot in at least 3 of the last 4 November general elections (2018–2024). Percentages are precinct totals from the official state voter file — no individual voter information is shown. Precincts with fewer than 400 active voters are excluded.
How San Luis Obispo County voted for president
Election results are public records.
San Luis Obispo County at a glance.
San Luis Obispo County had an estimated 281,843 residents in July 2024, the 24th most populous of California's 58 counties, down 0.2% since the 2020 census. Of those, 233,591 are 18 or older, the voting-age population, and 23.3% are 65 or older. Its 183,260 active registered voters equal about 78.5% of that voting-age population.
It covers 3,301 square miles of land (85 people per square mile), and 43.1% of residents live outside any incorporated city or town. The largest cities and towns are San Luis Obispo (49,729), El Paso de Robles (Paso Robles) (31,568), Atascadero (29,743), Arroyo Grande (18,249) and Grover Beach (12,534). The American Community Survey (2020-2024) puts it at a median age of 40.4, a median household income of $97,446, 39.8% of adults 25 and older holding a bachelor's degree or higher and 62.1% of occupied homes owned by the people living in them.
In 2024, 150,766 votes were cast for president, about 64.5% of the voting-age population; the Democratic ticket took 53.9% and the Republican ticket 43.1%. The two-party margin moved from D+5.4 in 2008 to D+10.8 in 2024.
- Population (2024 estimate)
- 281,843
- Population (2020 census base)
- 282,448
- Voting-age population (18+)
- 233,591
- Active voters per 100 adults
- 78.5
- Residents 65 and older
- 23.3%
- People per square mile
- 85
- Living outside incorporated places
- 43.1%
- Land area
- 3,301 sq mi
- Median age
- 40.4
- Median household income
- $97,446
- Adults 25+ with a bachelor's degree
- 39.8%
- Owner-occupied homes
- 62.1%
Largest cities and towns
- San Luis Obispo 49,729
- El Paso de Robles (Paso Robles) 31,568
- Atascadero 29,743
- Arroyo Grande 18,249
- Grover Beach 12,534
Presidential vote, 2008–2024
| Year | Democratic | Republican | Margin | Votes cast |
|---|---|---|---|---|
| 2024 | 53.9% | 43.1% | D+10.8 | 150,766 |
| 2020 | 55.3% | 42.2% | D+13.1 | 159,681 |
| 2016 | 50.6% | 42.3% | D+8.3 | 124,575 |
| 2012 | 49.0% | 48.0% | D+1.0 | 117,597 |
| 2008 | 51.4% | 46.0% | D+5.4 | 132,653 |
Sources: U.S. Census Bureau Vintage 2024 population estimates and 2024 Gazetteer; American Community Survey 2020–2024 5-year estimates; certified county presidential returns. Growth, density and turnout are simple arithmetic on those figures.
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