California voters are as diverse as its geography, from mountain ranges to valley farmland to forests and beaches. So a look at official voting results released this month shows notable differences in who turned out, how we voted, and where we voted.

More than half of California’s record 17.8 million ballots cast came from just five counties: Los Angeles, San Diego, Orange, Riverside, and Santa Clara. That’s partly because most of our counties are small and reported fewer than 100,000 voters this election. 

The larger, urban areas typically rolled out new gadgets and relied more on polling places or vote centers. In mountainous counties like Siskiyou, voters preferred to vote by mail. Along the southern border, many Imperial County residents faced language barriers.

The diverse state makes for varied voter outcomes in turnout and registration rates. Who knew Alpine County would cast the fewest ballots? Or San Bernardino would have the lowest registration rate among the largest counties? Or that the counties with the lowest turnout would have the highest in-person voting? We dug into the Secretary of State’s data from the recent election and from the 2016 general election to show the numbers behind this fall’s vote.

For purposes of this data dive, percents are rounded off. In addition, we considered small counties to be those with up to 99,999 voters this election, medium-sized counties between 100,000 and 499,999, and large counties above 500,000. That made for 31 small counties, 18 medium-sized, and nine large ones.

Follow along for a fast look at our state’s election results.

Where were the most — and least — ballots cast?

Los Angeles County didn’t just cast the most ballots in California, it cast the most of any local jurisdiction in the nation, according to the county’s registrar. Tiny Alpine County, which borders Nevada just east of Sacramento and south of Lake Tahoe, didn’t even crack 1,000 ballots. 

Los Angeles County: 4.34 million ballots cast

Alpine County: 749 ballots cast

Counties with the highest registered voter turnout

Statewide, about 81% of registered voters turned out to vote, a rate not seen since Led Zeppelin’s heyday and Jimmy Carter’s presidential win in 1976. The counties below helped California boost its civic engagement.

Small countiesMedium-sized countiesLarge counties
Nevada County 89%Sonoma County 90%Orange County 87%

Counties with the lowest registered voter turnout

But not all is golden in California election turnout — and some counties were below average. In some cases, such as with Los Angeles, tallying record numbers of ballots didn’t translate to voters turning out at high levels. Low turnout areas tend to be lower income, less educated, and more ethnically diverse, a Votebeat analysis showed. 

Small countiesMedium-sized countiesLarge counties
Imperial County 68%Kern County 73%Los Angeles County 75%

Counties with highest vote-by-mail ballot use

When Bill Clinton won the presidency in 1992, about a fifth of California voters had used their vote-by-mail (or absentee) ballot to vote. That number has been increasing since then. The pandemic this year prompted California to mail all registered voters their ballot, driving the number to 87%. Here’s a caveat about where more voters used mailed ballots: counties are allowed to count mailed ballots that are dropped off at vote centers or drop boxes in this category. Our analysis here excludes three small counties that already exclusively voted by mail — Alpine, Sierra, and Plumas — as well as six counties that counted every ballot as vote by mail even if cast in person. Those counties include Lassen, Sutter, Mariposa, Stanislaus, Trinity, and Merced.

Small countiesMedium-sized countiesLarge counties
Mendocino County 99%Butte County 96%Santa Clara County 93%

Counties with most voters voting in-person

Despite the pandemic and social distancing concerns, some voters did not trust their ballot would be counted if they cast it through the mail. Or, they needed help voting or just like to vote in person. While it is not conclusive, some studies have linked vote-by-mail to higher turnout. So it makes sense that Imperial County and Los Angeles County — both with lower turnout — would head the list of in-person voting. 

Small countiesMedium-sized countiesLarge counties
Imperial County 38%Tulare County 15%Los Angeles County 21%
(top third statewide)

Counties with largest turnout increase and decrease from 2016

This is a category where it didn’t matter if a county was urban or rural —almost all saw a bump in registered voter turnout compared to the 2016 general election. But three counties (Imperial, Tulare, and Plumas) actually reported decreases in turnout, even as they saw higher than average registration growth. An Imperial County spokesperson said, “there were also many of our voters that were not accustomed to receiving mail-in ballots.” In Plumas, a BallotTrax program confused voters by sending canned messages about polling places, despite having none.

San Joaquin County: largest increaseImperial County: biggest decrease
From 69% in 2016 to 80% in 2020From 70% in 2016 to 68% in 2020

Who’s doing the best job of registering voters?

About 88% of eligible Californians are now registered to vote. The last time California topped that figure was in 1940 when it surpassed 96%, an analysis of historic data shows. A large and growing population might make it difficult to keep registration levels high, but some counties show it can be done.

Highest Voter Registration Rate: Marin County 97%

Lowest Registration Rate: Merced County 72%

Highest Voter Registration Rate by County size:

Small countiesMedium-sized countiesLarge counties
Nevada County 96%Marin County 97%Los Angeles County 95%

Lowest Voter Registration Rate by County Size:

Small countiesMedium-sized countiesLarge counties
Merced County 72%Tulare County 75%San Bernardino County 83%

Where registration rates have improved — and gone south

The good news for almost all counties is that they increased their voter registration rate since the 2016 general election — with one notable exception. San Francisco’s registration rate decreased by 1 percentage point to 78% this election cycle. Tiny Alpine County, however, outdid the rest of the state when it reported the biggest increase, jumping 18 percentage points from 76% to 94%. Among large counties, San Bernardino shifted the most, jumping 15 percentage points from 68% to 83%.

Small countiesMedium-sized countiesLarge counties
Alpine County
18 percentage points
From 76% in 2016 to 94% in 2020
Tulare County
16 percentage points
From 59% in 2016 to 75% in 2020
San Bernardino County
15 percentage points
From 68% in 2016 to 83% in 2020

This is why every vote matters

In Orange County, one voter wrongly marked the choice for a school board candidate outside the designated box. The result was a literal tie, leaving the seat’s fate up to the school district.

Five—yes, just five— votes made the difference in the Santee City Council race, giving the nod to Republican Dustin Trotter. Thirty-six ballots were excluded from the original count for reasons including missing or mismatched signatures and a postmark after election day.

This coverage is made possible through Votebeat, a nonpartisan reporting project covering local election integrity and voting access. In California, CalMatters is hosting the collaboration with the Fresno Bee, the Long Beach Post and the UC Berkeley Graduate School of Journalism.

This story was updated to clarify the five counties that made up more than half the state’s record ballots cast.

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Michael Lozano leads CalMatters’ Youth Journalism Initiative assessing the state of California’s journalism education and industry pipeline. He previously covered election administration for CalMatters...