Glass House: California Legislator Tracker


About the California Legislator Tracker

We Californians elect 120 legislators to make important decisions about what life is like for all 40 million of us. How schools and colleges are run. What roads we need and what cars we drive. Whether our streets are safe and our environment protected. And how we care for the elderly, the poor and the homeless.

Most of us don’t know who these people are, but you should. It makes a difference in how they vote, especially when they have to balance the public interest versus special interests. This guide is your introduction, with information about each legislator’s personal background, their political profiles and their policy priorities. Let them know what you like and what you don’t like. It matters.

About the Data

The data included in the directory come from various vetted sources. See specific sources for each section below.


Is it really possible to depict a person’s political ideology in all of its nuance and complexity with a single number? Of course it isn’t. But by looking at how often certain legislators vote with one another, we’ve come up with a starting point to give readers a better sense of how lawmakers stack up.

To do it, we gathered up all the “aye” and “no” votes from every assembly member and state senator from the 2019-2020 legislative session. That includes floor session votes, but also votes in committee. Even after excluding resolutions, which are just procedural or symbolic, we were still left with 13,922 separate roll calls to analyze. We then fed that long list of up and down votes into a piece of software written by political scientists at UCLA, USC, the University of Georgia and Rice to come up with a measure of ideological “distance” — how close or far apart different lawmakers are to one another are based on their voting behavior.

An example: San Francisco’s David Chiu and San Diego’s Lorena Gonzalez, both liberal Democrats, voted together about 95% of the time in the last session. Contrast that with Rocklin Republican Kevin Kiley, whose votes overlapped Chiu’s only 65% of the time. Feed those patterns through the software and Chiu and Gonzalez are ideological neighbors whereas Kiley lives on the farside of town from both of them.

That “distance” is assigned a number between -1 and 1, but we converted it from 0 to 100, with all the liberals clustered around 0 and the conservatives at the top of the range.

Political scientists have been tinkering with some version of this method, called NOMINATE, since the early 1980’s. There are, of course, other ways to compare lawmakers’ political proclivities: comparing how they vote on certain legislation, how much money they raise from specific interest groups or what grades they’ve been assigned by advocacy organizations. So why do it this way?

All of those methods require some tricky judgement calls to be made.

What, for example, does a lawmaker’s C-grade from an anti-abortion group tell us about their ideology? What if that same lawmaker also got an A-rating from the Sierra Club? Boiling the analysis down to just the “yes” and “no” votes of different legislators does away with that subjectivity, leaving only numbers. And numbers don’t lie.

You can read more about how we’ve used this method in the past here.

Topic leadership

For all of the major topics in California, activists and lawmakers know who the key leaders are within the Legislature. Key leaders are those with the most influence and activity on these issues, often because they are experts on the topic with the power to build the support needed for passage. Sometimes these leaders are chairs of the topic committees, but not always. Most often these days, they are also Democrats because Republican lawmakers have a tough time building a coalition while the Democratic Party holds a supermajority of seats. These topic leaders were identified by our CalMatters reporters, who work full time with all of the stakeholders on these issues.

Contact information

Contact information comes from the official California state Senate and Assembly websites.

Social media information comes from CalMatters data collection.

Biographical information

Sexual orientation data is from the Legislative LGBTQ Caucus, which provided the names and identified orientations.

Legislator gender and race/ethnicity data come from the California State Library. Note: The underlying ethnicity data from the California Research Bureau defines “multi-racial” as legislators with parents of two different non-white ethnicities. Legislators with one white parent and one non-white parent are categorized as the non-white ethnicity. Census racial/ethnicity definitions vary from this definition.

Legislator birth dates, birth places and residence were sourced from Political Data Inc. and CalMatters data collection from elected official offices.

Much of the personal demographic data was originally collected by CalMatters journalists Matt Levin and Orlando Mayorquin for the interactive “How diverse is the California Legislature?”.

Legislators background data come from official ballots on the California Secretary of State Prior Elections page.


Committee assignments come from the official California state Senate and Assembly sites. Only standing committee assignments and roles are specified.

Committee descriptions were adapted from the committee websites or written by the CalMatters editorial team.

Special interest groups

Included special interest groups were chosen by the CalMatters editorial team to reflect a variety of areas and perspectives.

Group descriptions were written by the CalMatters editorial team.

District demographics

Voter registration data come from the California Secretary of State's Report of Registrations as of October 2020.

District demographics for race/ethnicity, median household income, median age, poverty rate and educational attainment come from the U.S. Census Bureau 2019 American Community Survey 5-Year estimates.

District map boundaries data come from the Statewide Database.

District partisanship

How do you know if a district is a sure thing for Democrats, a Republican lock, a toss up or something in between? Elections are unpredictable. But taking a few data points on voter registration, past voter behavior and some demographic information about a district’s voters can give us an informed guess.

That’s what we did with our partisan lean score. Data nerds, eat your heart out: This part gets a little technical.

We started by looking at both Assembly and state Senate elections going back to 2012, the first election that made use of the current electoral map. Our main question: What determines — or, at least, predicts — whether a district will elect a Democrat or a Republican (1) in the next election?

There are a bounty of possible variables to choose from. Do more Democrats live in a district or Republicans? How many more? Which party won the last election? By how much? Has the district flipped from one party to the other recently? And what about the voters themselves — their income, race and education level?

After gathering all of those numbers, our next step was to figure out which of these data points are actually important. Why not just use them all? Trying to predict the next election based solely on how many Democrats live in a district isn’t likely to be very accurate. But it’s also possible to include too many variables. A kitchen sink approach — including, say, the incumbent’s birthday month or hair color — is a good way to construct a very precise description of the past that isn’t flexible enough to tell us anything about the future. Statisticians call that “overfitting” a predictive model.

To balance that trade-off, we used a selection method common among statisticians and data scientists that rewards variables that add useful new predictive power while also adding a small penalty to each new factor you consider.

With our new list of vetted variables, we plugged them into a logistic regression model — a statistical method that’s often used to make predictions about things with only two possible values. In this case, those two values are “Democratic” and “Not Democratic.” With a little tweaking, those predictions can be converted into probabilities, which allows us to say something like the following: “There’s a 18.5% chance that a Republican will win the next election in Senate District 14 in the Central Valley.”

We should take that number with a few heaping tablespoons of salt. With just a few variables — none of them based on current polling — there’s no way we can put the odds on a future legislative race with that kind of precession. So instead, in our last step, we took these probabilities and grouped them into five rough categories: “safe” Republican and Democratic seats, partisan districts that “lean” toward one party or another and “toss ups.”

(1) Because one member of the Assembly, Chad Mayes of Rancho Mirage, is a political independent and therefore neither, technically we wanted to predict whether a district will vote Democratic or not Democratic.

Election results

Election results data come from the California Secretary of State's Elections Statistics.

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Glass House: California Legislator Tracker is a team effort, made possible by the following:

Developers: Erica Yee and John Osborn D'Agostino

Product manager: Sapna Satagopan

Designer: Nick Garcia

Political reporter: Ben Christopher

Photo editor: Anne Wernikoff

Reporters: Rachel Becker (environment), Jackie Botts (poverty), Ricardo Cano (K-12 education), Ana B. Ibarra (health), Matt Levin (housing), Byrhonda Lyons (justice), Laurel Rosenhall (state budget), Mikhail Zinshteyn (higher education)

Analytics manager: Shyla Nott

Membership director: Trevor Eischen

Product engineer: Ron Chambers

VP, product strategy: Kim Fox

VP, engagement: Margarita Noriega

Editor: Dave Lesher