On eve of Prop. 50 vote, see how voter registration has changed in SLO County
California voters will take to the polls tomorrow for the statewide special election to decide on a single ballot measure.
Proposition 50 seeks to allow the boundaries of California’s congressional districts to be temporarily redrawn by state lawmakers instead of a citizens commission.
If passed, Prop. 50 would result in California changing its district lines until 2030 in an attempt to add five new Democratic seats to Congress, counterbalancing Texas’ Republican-favored redistricting.
San Luis Obispo County’s district boundaries would not be impacted, but the ballot measure has spurred advocacy from both political parties protesting or justifying the gerrymander.
More people registered as Republican from last year’s presidential election to now — in fact, Democratic registration sank slightly — but looking at the last 20 years of local voter registration from the state, the very opposite is true.
California held a special election in 2005 under Gov. Arnold Schwarzenegger, which also coincidentally included a proposition related to the redistricting process. That measure failed.
The Tribune looked back at the last two decades of voter registration data from the Secretary of State’s Office to analyze party registration trends in SLO County from the 2005 special election to tomorrow’s.
Voter registration in SLO County over the last 20 years
Each year’s data was recorded 15 days ahead of the election, except for 2025, which reflects data as of Monday, Oct. 27 — eight days ahead of the special election.
The data shows there were more Republican voters in SLO County 20 years ago — 65,899 — than there are today, despite there being a total increase of nearly 28,000 voters since then.
The trend shows Republican registration steadily decreased until 2014 — to 59,193 — before it began increasing again, leveling out below 64,242 now.
Meanwhile, in the same 20-year timeframe, Democratic registration in the county grew by nearly 15,000 voters overall, from 54,770 in 2005 to a low point of 49,692 in 2014 before surging and similarly leveling out at 69,572 today.
Republican Party registration has remained overall more stable in terms of raw number of voters, but its share of total voters in the county decreased.
Overall, the Democratic Party’s share of total registered voters increased nearly 4 percentage points — from 35.4% in 2005 to 38.1% in 2025, around a drop to 33.1% in 2014 — while the Republican Party’s share shrunk by 7 points — from 42.6% to 35.2% over the two decades, with the exception of a less than half a percent increase from last year to this.
Republican voters had the highest percentage of total voter registration within the last two decades of either party in 2005.
