California voter registration by County 2006-2010

As we patiently await draft Californian congressional maps to be released later this year it is appropriate to check out the trends in voter registration. Given that the boundaries will inevitably change; comparisons by County rather than by CD are illuminating to say the least.

Below the fold for a comparison between October 2006 and October 2010 (midterm to midterm).  

CA Voter registration by County aka How California went Bluer.
Alameda 9,10,11,13 55.22% 17.52% D+37.70% 56.81% 15.71% D+41.10% D+3.40%
Alpine 3 35.74% 34.97% D+0.77% 38.2% 33.42% D+4.78% D+4.01%
Amador 3 34.91% 46.46% R+11.55% 33.14% 45.66% R+12.52% R+0.97%
Butte 2,4 34.57% 41.13% R+6.56% 34.71% 39.23% R+4.52% D+2.04%
Calaveras 3 33.94% 44.79% R+10.85% 32.32% 42.88% R+10.56% D+0.29%
Colusa 2 35.58% 46.5% R+10.92% 35.12% 46.15% R+11.03% R+0.11%
Contra Costa 7,10,11 48.12% 29.61% D+18.51% 49.8% 26.27% D+23.53% D+5.02%
Del Norte 1 36.52% 39.18% R+2.66% 36.65% 37.55% R+0.90% D+1.76%
El Dorado 4 30.71% 46.51% R+15.80% 30.19% 44.92% R+14.73% D+1.07%
Fresno 18,19,20,21 39.46% 45.29% R+5.84% 40.99% 40.96% D+0.03% D+5.87%
Glenn 2 32.54% 47.33% R+14.79% 31.25% 45.81% R+14.56% D+0.23%
Humboldt 1 41.35% 28.91% D+12.44% 42.59% 26.83% D+15.76% D+3.32%
Imperial 51 55.26% 26.34% D+28.92% 51.68% 26.66% D+25.02% R+3.90%
Inyo 25 32.14% 45.14% R+13% 32.28% 44.3% R+12.02% D+0.98%
Kern 20,22 35.7% 47.4% R+11.7% 35.31% 44.09% R+8.78% D+2.92%
Kings 20 37.89% 46.83% R+8.94% 36.15% 45.36% R+9.26% R+0.32%
Lake 1 43.29% 32.03% D+10.26% 42.96% 29.34% D+13.62% D+3.36%
Lassen 4 28.93% 46.62% R+17.69% 26.85% 47.82% R+20.97% R+3.28%
Los Angeles 22,25 – 39,42,46 49.74% 27.02% D+22.72% 51.4% 23.58% D+27.82% D+5.10%
Madera 18,19 33.7% 49.21% R+15.51% 35.28% 45.08% R+9.8% D+5.71%
Marin 6 51.73% 22.44% D+29.29% 54.61% 19.32% D+35.29% D+6.00%
Mariposa 19 32.3% 46.81% R+14.51% 31.07% 44.92% R+13.85% D+0.66%
Mendocino 1 46.27% 24.86% D+21.41% 47.2% 22.48% D+24.72% D+3.31%
Merced 18 45.01% 41.03% D+3.98% 46.27% 34.74% D+11.53% D+7.55%
Modoc 4 30.22% 49.34% R+19.12% 26.76% 49.24% R+22.28% R+3.16%
Mono 25 31.1% 38.64% R+7.54% 32.37% 36.91% R+4.54% D+3.00%
Monterey 17 48.23% 30.8% D+17.43% 53.45% 25.52% D+27.93% D+10.50%
Napa 1 46.08% 31.36% D+14.72% 47.2% 27.21% D+19.99% D+5.27%
Nevada 4 32.2% 42.96% R+10.76% 33.66% 40.04% R+6.38% D+4.38%
Orange 40,42,44,46,47,48 30.07% 47.9% R+17.83% 31.92% 43.18% R+11.26% D+6.57%
Placer 4 28.67% 51.43% R+22.76% 28.89% 48.23% R+19.34% D+3.42%
Plumas 4 33.36% 43.8% R+10.44% 32.37% 43.16% R+10.79% R+0.35%
Riverside 41,44,45,49 34.42% 45.7% R+11.28% 36.29% 41.87% R+5.58% D+5.70%
Sacramento 3,4,5,10 42.61% 34.54% D+8.07% 43.93% 33.76% D+10.17% D+2.10%
San Benito 17 45.05% 33.86% D+11.19% 48.18% 30.34% D+17.84% D+6.65%
San Bernardino 25,26,41,42,43 37.59% 42.41% R+4.82% 39.01% 38.46% D+0.55% D+5.37%
San Diego 49,50,51,52,53 34.16% 39.52% R+5.36% 35.92% 36.27% R+0.35% D+5.01%
San Francisco 8,12 54.43% 10.92% D+43.51% 56.26% 9.53% D+46.73% D+3.22%
San Joaquin 11,18 42.43% 40.6% D+1.83% 42.66% 38.96% D+3.70% D+1.87%
San Luis Obispo 22,23 35.08% 41.84% R+6.76% 34.96% 39.89% R+4.93% D+2.83%
San Mateo 12,14 49.42% 24.46% D+24.96% 51.77% 20.76% D+31.01% D+6.05%
Santa Barbara 23,24 40.39% 35.53% D+4.86% 42.37% 32.14% D+10.23% D+5.37%
Santa Clara 11,14, 15,16 44.9% 26.84% D+18.06% 45.88% 23.89% D+21.99% D+3.93%
Santa Cruz 14,17 53.04% 20.26% D+32.78% 54.83% 17.72% D+37.11% D+4.33%
Shasta 2 30.11% 49.18% R+19.07% 28.44% 47.25% R+18.81% D+0.26%
Sierra 4 31.1% 42.81% R+11.71% 29.11% 42.6% R+13.49% R+1.78%
Siskiyou 2 35.5% 42.3% R+6.80% 33.86% 40.96% R+7.10% R+0.30%
Solano 3,7,10 48.61% 29.12% D+19.49% 49.53% 26.16% D+23.37% D+3.88%
Sonoma 1,6 50.17% 25.71% D+24.46% 52.13% 22.74% D+29.39% D+4.93%
Stanislaus 18,19 40.23% 42.24% R+2.01% 43.38% 36.78% D+6.60% D+8.61%
Sutter 2 32.26% 49.51% R+17.25% 33.38% 46.28% R+12.90% D+4.35%
Tehama 2 33.3% 45.3% R+12.00% 31.43% 44.33% R+12.90% D+0.90%
Trinity 2 35.94% 39.07% R+3.13% 35.46% 35.54% R+0.08% D+3.05%
Tulare 21 34.25% 48.03% R+13.78% 34.54% 45.49% R+10.95% D+2.83%
Tuolumne 19 36.27% 43.73% R+7.46% 33.42% 42.63% R+9.21% R+1.75%
Ventura 23,24 38.07% 39.83% R+1.76% 39.76% 36.97% D+2.79% D+4.55%
Yolo 1,2 46.17% 27.53% D+18.64% 47.85% 24.64% D+23.21% D+4.57%
Yuba 2 33.96% 42.52% R+8.56% 33.43% 40.04% R+6.61% D+1.95%

Some observations:

In 2006 the Dems had a majority of registered voters in 6 counties, the Repubs in 1. In 2010 the numbers are 9 and 0 respectively.

In 2006 there were more Dems than Repubs in 23/58 Counties, in 2010 this has increased to 27/58.

Only 10 counties trended Repub between 2006-2010, 48 trended Dem. Of the 10 counties that trended Repub 7 of them are in the 2nd,3rd or 4th CD’s.

The biggest improvement between 2006 & 2010 came for the Repubs in Imperial at 3.90% and for the Dems it was in Monterey at 10.5%. No less than 24 counties improved for the Dems by more than Imperial did for the Repubs.

Repubs have a more than 10 point registration lead in 17 counties, Dems have the same in 21.

In four counties the voter reg gap is less than 200 voters!

Trinty – 6! (R)

Alpine – 35 (D)

Del Norte – 112 (R)

Fresno – 161 (D)

All of these Counties trended Dem between 2006 & 2010.

So what does this all mean?

As others have discussed at great length the future for the Republicans in California looks bleak. The areas of California that are trending Repub are almost entirely small inland counties with declining or very slowing growing populations. And whilst the Repubs still maintain sizable voter reg buffers in large counties like Orange and Riverside these counties are rapidly blueing.

For us Dems the news is looking great for obvious reasons. I expect by the 2012 General Election that the GOP will comprise less than 30% of registered voters in CA and that the Dems will be at least 45% – a huge 15%+ gap. Currently the respective numbers are 44/31.  

42 thoughts on “California voter registration by County 2006-2010”

  1. attempted nonpartisan maps of the San Diego seat draw Duncan Hunter into an area Obama won in the mid-50’s.  That county is near even right now.

  2. my posts here to redistricting stuff but voter registration is truely fascinating stuff.  Just a few comments.

    Since Motor voter came in and all these internet forms came about we have seen a huge decline in CA (and other states) in party registration.  The number of indies or others or no stated party has increased.  In 1970 there were only 4% of CA voteres who did register either democrat or republican and now the number is nearly 24%. These forms do not require you to check the party box so they are left unchecked and the same holds for race.  Many more voters now no longer check the race box.  

  3. I’ve said before that the Reeps have become completely uncompetitive at the state level, but at this rate they’re going to disappear everywhere except for a few overwhelmingly white rural counties. If you look at the counties where the Dems picked up 5 points or more, it’s…pretty much everywhere.

    Bay area:

    Contra Costa



    San Mateo

    That was a blue fortress to begin with.

    Central valley:





    These 4 are contiguous and include 2 of the 5 biggest counties. Kern and already-blue Sacramento and San Joaquin are turning blue at slower rates.

    Central coast/miscellaneous:


    San Benito

    Most of Monterey’s population is in the Salinas area. (I don’t know why it favors Dems much more than other ag-dominated areas do. It may just be water policy.)

    Coastal SoCal:

    Los Angeles


    San Diego

    Santa Barbara

    That’s all of ’em except for Ventura which barely missed the cut at 4.55%. These four counties have 40-50% of the state’s population.

    inland EMPIRE:


    San Bernardino

    The empire crumbles and turns blue.

  4. at numbers like this and think of how this state alone can help repair a lot of the damage in that Democrats wil feel from other states.

    I wonder, though, has there been any sort of active voter registration drive in recent years? There’s always some effort, but I’m talking about the sort of centralized, well funded operation for certain areas, if not the entire state, that drive these numbers. If not, you have to wonder if there are even more potential Democrats that might come out of the wood work. I won’t try to guess what the congressional districts will look like in 2012, but as long as the roughly seven million unregistered voters aren’t clustered in deeply blue districts and aren’t right-leaning voters, perhaps we can make the state’s delegation even more Democratic.  

  5. Increase of D registration in  a number of counties would have close to zero effect on the districts since they are so heavily D already.

    I note the following San Joaquin Valley counties, N to S

    West Valley[CD11, 18, 20] Probably the most critical area

    San Joaquin D+1.87[CD11]

    Stanislaus  D+8.61

    Merced D+7.55

    Fresno D+5.87

    Kings R+.32

    Kern D+2.92

    East Valley/Sierra Foothills[CD19,CD21]

    El dorado D1.07

    Amador R.97

    Calaveras D.29

    Tuolumne R1.75

    Mariposa D.66

    Madera D5.71


    San Joaquin D increase of 1.87 is anaemic.  Unless this is changed, it will remain tossup or lean D

    The Foothill counties[CD19] remain solidly R.  If combined with the opposite East Valley counties, the result will be likely R.  If the districts march down the valley in two columns, East Valley remains safe R, while the eastern districts become lean or tossup, with  a definite trend line D.  When you get to Kings and Kern[CD22], any district, unless gerrymandered to separate out heavily Hispanic areas, would be safe R.

    Coastal counties San Luis Obispo[D2.83] and Santa Barabara[CD23][D5.37], if combined would result in a likely D district, trending [because of the City of Santa Barbara] heavily D.  The 2 counities have allmost enough people for a CD.

    The Imperial [R3.90] which, in my opinion, would be excised out of the San Diego County Districts seems to be trending R. This is unfortunate because it would be a signiifcant factor, otherwise, in blueing a eastern Riverside district.

    The Inland Empire[CD49, 43-5, possibly 42] districts San Bernardinao and Riverside, are bluing heavily, indicating that new districts created there would be more D than in 2000. These counties also, are probably a couple of the fastest incrasing.  The devil would be in the details, but I suspect that the districts centered on the principle cities of each county would be D.  Other districts would be from Safe R to swingish.

    Ventura-[CD24] has enough for a district strictly inside the county.  I think, at best, the Rs could gain a tossup, but more likely a Lean or Liley D district would be the result.

    Orange [CD46-48][D6.57] could have a significant effect influencing 2 Districts instead of 1 in the county [out of 4].  May not be immediate, but a Republican who starts the decade in a North Orange district should not be too comfortable over the decade.

    Sacramento.[CD03, CD05] [D2.87]  The county has population for 2 districts.  One for Sacramento city, the change in registration would have no effect.  The question is what is happening outside the city, which I think now is tossup or lean R.

  6. look at registration stats for CA and I don’t have time to do a detailed post on it.

    CA is heavily democratic but its based on a massive edge in Bay area & LA county and that is reflected.

    1. I believe CA has a 1.5 million voter edge to the democrats in voter registration.  What is the democratic edge in LA SF San Mateo-Santa Clara-Alameda-Contra Costa Solona and Marin county?  I suspect that the entire D edge might be there or at 90% of it?

    2. What’s the implications for redistricting?  In 2010 in LA’s 14 congressional districts and in the 10 Bay area districts Boxer won by around 1.4 million votes.  In the other 29 congressional seats she lost by 600K.  The democratic vote is very deep in Bay area & LA county while the rest of the state is not nearly as blue.  

    That’s why we see several maps here stretching the Bay Area and Downtown LA.  The democratic hope for 2011 redistricting is to attach the Bay area & Downtown LA strongeholds to outlying areas.  

  7. The voter reg advantage for dems in CA is 2.3 million and rising. As you can see from this diary the dems advantage is growing from all areas for the state. As i said in so many words in the diary – 48/58 counties in california are now more democratic than they were 4 years ago.

    I agree with you re redistricing. Southern Cal will be also interesting to watch beacuse of the near parity in san diego and declining GOP advantage in orange and riverside.

  8.  I know many of my friends who identify as independents. However, one of those same friends is extremely opposed to the death penalty and really wanted to go to the rally to restore sanity.  

  9. I think the movement of the national Republican party toward a European-style right-wing nationalist party has hurt them badly in CA.

  10. In 2010, Whitman only managed to crack 60% in three counties, even managing to slightly under-perform in Kern County and quite dramatically in Lassen County (negative 15%), as well as a few other counties. It’s not a healthy picture for Republicans.

  11. as a point of reference that voter registration is not a beat all end or for partisan prefermance in CA or many other states.

    1. In CA in 1966 democratic registration was 56% and Reagan won by 1 million votes in his 1st Gov term. CA was 53% D in 1984 and Reagan won CA by over 56%. The % of democrats in CA in 2010 is 43%.  So as the democratic % of registered voters have declined since 1984 the state has turned bluer.  In 1970 the gap between the parties was 14% and I believe that is a bit less then it is right now.

    2. Republicans tend to run ahead of party registration numbers except in LA & Bay area.  Democrats and Indies outside of Bay area & LA county tend to be more  moderate or conservative.  For instance Boxer won 18 counties in 2010.  She won by a landslide but who the most counties–yup Carly F.  There are 27/58 counties with D registration advantage but 1/3 of those D counties voted for Carly F.  That’s a typical pattern as the GOP in CA tends to run around of its party numbers. I think the old rule of thumb was 5% but times change and I am sure what that number is now.

  12. right after they finish lending them to Nevada and Arizona.  New Mexico is next but they’ll play with Texas after that.  

  13. Texas will be turning (more?) Democratic sooner rather than later for the same reason that California was so resistant to the wave. And while Texas will almost certainly be a more conservative and more Republican state than California is, I imagine the Democrats will have far more success there than Republicans will in California because they are willing to run candidates who are better fits for the state.


  14. That’s why Obama won Butte, Trinity, San Luis Obispo, San Diego, Riverside, Nevada, and Mono, and nearly won Orange.

    (I know the inevitable response will be “but 2008 was the Democratic high-wave point!” well, so was 2010 for the GOP, which is pretty sad.)

  15. comment  on this point.  You are correct in the last number of years the GOP has lost a few counties that they have a registration advantage in. I wonder how many over the last few election cycles?  

    If you have time I would love to see your analysis of previous statewide elections for competitive races.  Don’t do AG 2006 but Presidential senateGov and what not.  I like to look at what counties that have a democratic edge that the GOP carried and vice versa.  CA SOS has tons of past voter registration stats as counties have changed over the years.

    I find fascinating to look at legislative seats.  How many GOP assemblyman are in seat where the democrats have an advantage and how many seats do the democrats have with a GOP advantage.  I look forward to any work you can do on this. The old rule of thumb was that the GOP had to be within 5% of registration numbers to have a chance at winning an assembly seat.  Is that still true? I don’t know.

  16. If a Repub has to be within points of voter reg to stand a chance then a Dem would have to be within 10 to stand a chance owing to the fact the Indy/DTS voters in Cali are more likely to vote Dem than in other states.

    Actually both parties run above their reg numbers. They have to as 25% of the electorate is neither Dem nor Repub.

  17. GOP incumbents with Dem voter reg advantage: 26, 30

    Dem incumbents with GOP voter reg advantage: 5,

    All 3 of these districts are trending Dem.

    If the trend of the last 4 years continues then by about 2018 the GOP will be about 25% of registered voters.

    As for statewide races yep the GOP carried some slightly dem counties and vice versa.

    But the overall trend is strongly to the Dems.

    Statewide Voter Reg –

    42.48% Dem 34.33% GOP – 2006 Midterms

    44.08% Dem 31.02% GOP – 2010 Midterms

    The trend is quite clear.

  18. as I noted above in 1970 96% of voters in CA were registered as R or D.  Today its closer to 75%

    That being said I love to see the stats on my point for the last 20 years or so.  

  19.    is the biggest trend in voter registration in California in the last few decades. There are also more third party registered voters these days, with four small parties on the VR forms along with the big two. The Libertarian, Green, Peace and Freedom and American Independent Parties all have grown, though some of the latter party are actually people who think they are registering independently, which is called “Decline to State” in Californian terminology.

       While it is most likely that California nonpartisan voters are overall more Democratic than in other states they tend to reflect the communities they vote in. Coastal area independents are more progressive, especially on environmental and social issues, while the inland independents are closer to the GOP.  

  20. I had this crazy idea and as far as I know its not been knocked down.  Some have tried to explain it away but the logic still holds for me.

    1. The GOP currently holds 19 seats and these seats have 1 million in excess population.  That’s nearly 20 1/2 seats.  I assume the nonpartisan commission will draw fair lines exactly how does 20.5 seats become less then 19?  Perhaps if 2 million (nearly three congressional seats)in GOP population is removed and one million in democratic population is added you might see a reduction but how can one assume this odd arrangment will occur in a fair redistricting.  Plus where will the 2 million in GOP population go?

    2. The GOP nearly won CD11-CD18-CD20 in 2010 and they happen to be next to GOP seats needing to shed part of that 1 million in population.  So logically in a fair redistricting how can you weaken the GOP 19 without shifting some population to seats the democrats hold by narrow margins?

    3. Yes the GOP has some gerrymandered seats but so do the democrats.  If you unwind some GOP seats you will also put in danger democrat seats.

    I look for about 15-18 GOP seats that are fairly solid and then 7 to 10 seats that will be competitive.  The one thing the voter registration stats show us in CA is that democrats have very very deep numbers in certain areas but over 1/2 of the state is competitive.  In a fair non gerrymandered redistricting you will not see democrats concentrated in very blue seats while the rest of the state is tinged Red

  21. And the honest answer is i dont know. It depends on which part of the population is hacked off the gop seats and which dem seats it moves into.

    Honestly i think the new boundaries are so unpredictable that anything could happen.

  22. It’s pretty simple. Of 19 Republican districts, eight (03, 24, 25, 26, 44, 45, 48, 50) voted for Obama. Even if these districts shrink, the population they give up won’t necessarily be GOP.

  23. Kings county is a bit of an outlier. Don’t understand why it trended r when the rest of so cal is moving D.

    San Joaquin – Yep the Dems there need to step it up. However the part that is in the 11th went from a 13k deficit to a 6k deficit in 4 years. The whole of the 11th went from a 5.6% voter reg deficit to a 0.3% voter reg deficit in 4 years also.

    In So Cal any GOP incumbent in San Diego should be nervous. Each CD in san diego is trending towards the Dems, as is the san diego part of each of those districts.

    Might do a diary breaking down some of these counties :)

  24. idea of this nonpartisan commission is to eliminate political gerrymandering and I think people will be disappointed if we will see very odd seats for instance.  If see Santa Barbara area connected to Bakersfield.  Or Imperial county (farm country) to downtown San Diego.  Or even Bay area suburbs connected to Central valley farm country.  

    I expect that we will see a seat based on San Jose instead of dividing it several ways.  

    I personally also expect to see several more minority majority seats in CA.  

  25. There would almost have to be more majority minority seats.

    Not sure about San Jose could go either way. If urban seats are kept urban and rural seats are kept rural then this is bad news for the GOP i suspect.

  26. points

    1. The congressional districts that were carried by Obama in 2008 and also elected a GOP congressperson in 2008/2010.  Exactly why do you think 2012 would be different?  Ticket splitting seems to be alive and well in  CA in congressional races.  Several GOP members survived Obama win while several democrats won Bush2004 districts.  

    2. What happens if this oversized GOP districts lose democratic voters instead of GOP voters? When one rolls the dice does one expect to roll heads everytime?  You can’t expect to win every redistricting decision on every seat in CA can you?  

    3. Who gets these GOP voters from these seats that Obama won?  If voters are taken from CD45 & CD48 that are republican are we going to see another GOP leaning seat in Riverside county?  Will the Capps seat go from democratic to tossup?  You can’t just banish GOP voters to Utah.  They have to go somewhere.

    4. Speaking of elections by my eyeballing every seat that Obama carried that is now held by a GOP congressman apparently went by a nice  margin to Carly F. Do you have stats on this?  Obama won CA by 61% but Boxer won only 53%.  It looks like these districts that went democratic in 2008 went back strong to the republican side in 2010.

    I don’t think the questions that I raised in my previous posts have been truely addressed and answered.  I see alot of wishful thinking that the nonpartisan board will somehow address every redistricting issue in CA to the advantage of the democrats.


  27. My contention is simply this. Republicans are in real trouble in california because the changes in voter reg show that the upswing to the democrats is so seriously large across the state as a whole. Not trying to predict what new boundaries are going to look like but think that the Democrats will make serious gains across the board at a cd level because a rising tide lifts all boats. Consider this – between october 2006 and 2010 10/58 counties trended republican. The largest? Imperial 94k reg voters. How many count with more than 100k reg voters all of which trended dem? 30!

    As I say a rising tide lifts all votes. Btw 5 of the gop ten have less than 20k reg voters have less than 50k.

  28. 1. why wouldn’t 2012 be different is a better question. it’ll be a new map that probably won’t advantage the Republicans, districts that flew under the radar in 2008 (CA-44, CA-45, etc) will be targeted by the DCCC, demographic trends will continue to erode the Republican lean of these districts, etc…this ridiculous suggestion that the Republicans were ok in 2008 so they’re ok in the future makes perfect sense in GOP-Talking-Points-Land, I’m sure, but here on SSP it’d be nice if you could avoid that.

    2. what are you even talking about anymore?

    3. Possibly. That’s a question mark.

    4. I think Jerry Brown won CA-03, actually. The fact that 2010 was the Republicans’ best-case scenario says a lot about how fucked the Republicans are in Cali.

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