CA Maps by Cook Report – Analyzed

At the end of last week the Cook Political Report came out with a set of district lines as an approximation of what the Citizens Redistricting Commission would create.    The lead to their story reads:

What happens when politicians who have grown accustomed to the luxury of choosing their voters are forced to cede redistricting authority to a group of amateur citizen commissioners? In this gigantic laboratory of reform, more than a handful of incumbents are rightfully fearful they will be sacrificed for science. House Editor David Wasserman maps out some of the most talked-about speculative scenarios and outlines who could be in trouble. A “blank slate” commission map could endanger up to 15 incumbents and create as many as five new opportunities for Hispanic candidates

The Cook report identifies a number of Congressional members who are in the most gerrymandered seats and need to be concerned about redistricting.  These include:


Dan Lungren (CA-03)

Elton Gallegly (CA-24)

David Dreier (CA-26)

Gary Miller (CA-42)

Ken Calvert (CA-44)


Jerry McNerney (CA-11)

Sam Farr (CA-17)

Dennis Cardoza (CA-18)

Jim Costa (CA-20)

Brad Sherman (CA-27)

Howard Berman (CA-28)

Laura Richardson (CA-37)

Grace Napolitano (CA-38)

Bob Filner (CA-51)

and whoever wins the CA-36 special election in June.

Criticizing maps is easy, while drawing them can be a challenging task.  Some of the shortcomings we identify in the Cook Plan could be a function of them not having access to the same data tools.  However, given that this is the first widespread release of a legitimate plan from a trustworthy source, it requires some honest analysis.

Overall there are several things that are right and wrong with the plan.

What’s right about the Cook Maps:

1)    The shift from the coastal area to the Central Valley and Inland Empire reflect a current reality – and an unavoidable result of the redistricting process.

2)    Bay Area districts don’t cross the Bay Bridge or Golden Gate.  This preserves county/city lines and communities of interest, but would weaken the city of San Francisco if the same rule was applied to the Senate districts.

3)    The plan appears to keep more cities and counties intact than the 2001 plan.

4)    While competitiveness is not an official criteria, it is meaningful in the public’s eye, and this plan makes several districts more competitive.

What’s wrong:

1)    The plan plays way too loose with the Voting Rights Act, retrogressing several Section 2 districts, splitting the Section 5 county of Merced, and putting Kings County into a totally different seat.  In fact, it appears to water down the Citizen Voting Age Latino Population in every Section 5 district except Herger (which is only 10% Latino CVAP currently).

2)    Several districts, particularly the Dreier (CD 26) seat, cross county lines unnecessarily and oddly so that they run afoul with several criteria, including geographic compactness and maintaining communities of interest.

3)    The City of LA does not seem to be preserved at all.  Several little cities are merged with the larger city.  This could be due to the inability to truly see the city lines in the application they were using.

The data tables on my page go through each district to review ethnic and partisan changes in the districts.  The analysis was done only after redrawing the lines in Maptitude, the database/mapping software that is being used by the Commission.

The data used in this analysis comes from the latest US Census release and the Beta release of data from Political Data Inc. which allows census-block level analysis of party affiliation, voter turnout, results and electoral modeling.

Ethnic Breakdown Tables

The charts on my site provide ethnic breakdown of the 53 districts in the Cook plan.  Section 5 and Section 2 Majority-Minority districts are highlighted in red.  A Majority-Minority district for the purposes of this analysis is the most liberal interpretation – one that is majority Latino in 18+ Population or Citizen Voting Age Population.

Of the 11 Majority-Minority Latino or Section 5 seats in California, all but three of them have retrogressed under the Cook Plan.

Several other interesting seats are highlighted in orange.  These include the Barbara Lee and Laura Richardson seats, both of which lose African American voting strength, while Mike Honda and Doris Matsui see slight increases in Asian populations.

Partisan/Voting Behavior Breakdown

The the second set of data charts voter registration and partisan turnout.  This is built from census-block level geocoded County voter files and only available through Political Data Inc.

The double digit shifts AWAY from the party in control of that seat are noted in red.  The only double-digit improvements are for Billbray and Royce, however the Billbray improvement could have to do with a district number-switch that was uncorrected from the Cook Plan.

Note on Data: Ethnic totals are 2010 official Census release for redistricting.  Citizen Voting Age Population (CVAP) is estimates from the Census Department released in February 2011.  Voter registration data is directly from the current statewide voter file managed by Political Data Inc.

This Memo availalable in PDF: Cook Uncooked

Maps and Charts: Cook Uncooked

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46 thoughts on “CA Maps by Cook Report – Analyzed”

  1. This is worth emphasizing:

    Of the cited Republicans (and the list is certainly incomplete as Duncan Hunter, Dana Rohrabacher, and Buck McKeon should definitely be included) the concerns are that they might be replaced by a Democrat under new lines.

    Of the cited Democrats, Dennis Cardoza shouldn’t even be on this list, because his district is no doubt VRA protected. More importantly, there is zero risk that seven of these seats might go Republican. The concern for Farr, Sherman, Berman, Richardson, Napolitano, Filner, and the CA-36 Democrat is that they might be at high risk of a successful primary challenge – but the seats would no doubt still be Democratic.

    In other words, the only Democrats listed here that have even a slim risk of being replaced by a Republican are McNerney and Costa – and the latter may be adequately VRA protected as well.

  2. Miller lives in Diamond Bar, which would be in Cook’s version of the 26th, so he’d be in with Dreier. That 26th is nothing like that commission would draw, it looks like a gerrymander.

  3. but Charlie Cook has drawn his lines in many ways just as I would.  I have all along that the decrease in population growth in Bay area & LA would push a map like this.

    The Bay area and LA city/county are diminished. They lost people and do not derserve to stretch out into rural area/suburban areas to perserve their power.

    There are seats that are draw in such a way to perserve hispanic strength. CHU & Costa are there.

    This is a very smooth map that looks  very close to what I have suggsted.  I might pack more hispanics into CD51 or CD53 but that’s me.

  4. I do have problems with CA-1, CA-26, CA-51, and CA-53 – which all look rather too similar to the current gerrymandered map (I honestly have no idea what they were thinking with CA-26).

  5. The biggest failure of the Cook Report’s map is splitting counties that need not be split (San Luis Obispo). Putting Kern in three separate districts is over the top. Having Tulare & Kings together in the same district makes  a lot of sense but using North Kern as filler isn’t viable. Same goes for peeling Ridgecrest off in to Jerry Lewis’ district. I that splitting a county needs to make sense. Using something demonstrative like the Sierra Nevada’s would be fine but willy-nilly splitting is a no go.

  6. the main reason the Commission will likely not draw CA-26 this way is b/c apparently Cook here is using inaccurate pop. numbers (apparently this was done prior to Census release) … and there’s no reason to combine LA Co. w/ anything south or east of it …

    here’s a map reflecting the actual numbers that have been released:


    the area in green is equal to exactly 14.99 congressional districts (off by only 5,903 persons) …

    other than in the lightly populated northern area, Cook follows a north-south “dividing line” (separating the green territory from the rest of CA) everywhere except where CA-26 goes into S. Bernardino Co., but he assumes that one of the LA districts will have to go east, while using actual numbers, there’s no need for it … (not sure what estimates he was using ?, but when I drew my map before the Census release, the numbers I saw also corresponded almost exactly to the green area having 15 districts: http://www.swingstateproject.c… )

    likewise, the area in red on the map is equal to exactly 16.01 congressional districts (off by only 6,917 persons) … (and within the red area itself, LA Co. is equal to 13.97 districts, while Kern, Kings and Tulare combined is equal to 2.04) …

  7. It just occurred to me that having 20 drawn that way includes at least five state prisons. Avenal, Corcoran, Delano I & II, and Wasco. That’s going to mess with that stats big time because those guys don’t vote.

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