Polarization


We’ve just released the July 2014 update of our state legislative ideology data set. Both legislator-level and state-level data are included, so you can use these scores for a number of different applications.

Big changes include:

  1. Expansion of the quantity of the data by 25% at the state level, and 11% at the individual level.
  2. Expansion of the breadth of the data to include 1993-2013.
  3. Filling in holes of the coverage even before 2012.
  4. Extensive cleaning and merging operations to minimize the effect of random noise.

Head over to the data site to check it out!

 

I have a new post over at the Monkey Cage blog at the Washington Post. It summarizes some of the posts I’ve made here, for an audience that probably hasn’t seen this blog before.

The one update is that the posts here used the most recent publicly available version of our aggregate state legislative data. That data includes the years up through 2011. The Monkey Cage post uses a preliminary update to our data set, that brings the data to 2013.

We are working on polishing this data for public release shortly.

In the meantime, here are the new plots using that data set. The graph below shows legislative polarization in each state, averaging across all the years of our data (approximately 1996-2013) and across both legislative chambers. Polarization is defined as the average ideological distance between the median Democrat and Republican in the state legislature.  Larger numbers indicate more division. The dashed line is the level of congressional polarization, included as a comparison (“US”).

state_polarization

About half of the states are even more polarized than Congress—which is saying a lot. At the same time, some states–like Louisiana, Delaware, and Rhode Island–have  relatively less polarized state legislatures. In Louisiana, both parties are fairly conservative, and in Delaware and Rhode Island, they are both fairly liberal.

One state that stands out is California. It is incredibly polarized. (And its most recent primary and redistricting reforms look unlikely to reduce polarization.) Unlike Congress, however, Democrats both dominate the state so thoroughly and no longer need to attain supermajorities to pass budgets, so this polarization is not as much of an obstacle to actual lawmaking in the California state legislature.

Another state that stands out is Wisconsin–the site of massive protests in 2011, a recall campaign against sitting governor Scott Walker, and even a physical fight between Republican and Democratic justices on its state Supreme Court.  It is perhaps no surprise that Wisconsin too is highly polarized.

Not only are states polarized, that polarization has increased over time. The graph below breaks down the trends in the ideology of Democrats and Republicans (measured by party medians) over time and across all 50 states. By convention, more positive scores represent more conservative preferences, and more negative scores represent liberal preferences. (One side-note: a data error exists in Washington State around the year 2000 and is being fixed.)

party_years

Most states have polarized over the past 20 years or so, but some more than others. Arizona, California, and Colorado are polarizing very fast. Nebraska—a state without formal political parties in its legislature—is polarizing very quickly too, though from a relatively low base.

Moreover, we are seeing asymmetric polarization, just as in Congress. Republicans have been getting more extreme faster than Democrats in more state legislative chambers, but this is by no means universally true across all states.

All in all, the picture we see in state legislatures is similar in many respects to Congress, but different in key points. The parties are pretty far apart on average, but that difference varies across the states. The parties are increasingly polarizing over time, but that too varies across state. Finally, we see cases of symmetric and asymmetric polarization. These new data on polarization at the state level—and the uneven pace of polarization across states—should help pundits and scholars figure out what’s driving polarization in our statehouses.

Over at American Legislatures, I show that, on the whole, polarization is asymmetric in the state legislatures. Republicans are polarizing faster across more states than Democrats. Examples include Tennessee and Colorado. But in lots of states, the patterns are different, where Democrats are leading the charge to extremism (eg, Idaho, Mississippi, and California). And both parties are polarizing roughly equally and simultaneously in places like Texas, Missouri, and Nebraska.

Read the whole post but here’s the key plot:

party_chamber_years

I have a new post about polarization trends in state legislative chambers across the country in the sister blog. Go there for the full details.

Here’s a little peek at the key plot.

polarization_chamber_years

Most state legislative chambers are polarizing, but a number are stable and a few are even going the other way.

I just posted an updated visualization of state legislative polarization over at the Measuring American Legislatures blog.

Here’s a small version you can look at, but see the full post and explanation here. Look at California at the top with massive polarization, and Louisiana and Rhode Island at the bottom with relatively small amounts of partisan division.

state_polarization_mcmc_1996-2011

 

 

My coauthor (Nolan McCarty) and I are releasing a new version of our state and chamber-level aggregate data. We have focused on two major updates:

  1. In all, we have 140 chamber-years of new data. These now include party data for Nebraska thanks to friend and coauthor Seth Masket, who generously provided the informal but well-known partisan affiliations for Unicameral legislators.
  2. The individual level data underlying this release has been extensively cleaned to minimize the random noise inherent in acquiring roll call votes from printed journals.

You can find the data here.

I recently posted the graph of my estimates of the two parties’ congressional candidates. In that post, I wanted to emphasize that moderation still exists, even in this polarized age. To highlight that point and make the plots prettier, I smoothed out the distributions.

However, that smoothing hid another very interesting take-home point from the 2012 candidate scores. There appears to be evidence of bimodality (two peaks) not only across the parties—that’s good old polarization—but also within the parties. Here are the unsmoothed plots that make that clear:

cands_house2012

cands_senate2012

No, those aren’t Halloween ghosts. It looks like both parties have two distinct wings, a moderate one and an extreme one. This visual inspection is backed up by test statistics from the Hartigan dip test for unimodality.

Feel free to download the estimates for all the 2012 congressional candidates here. The explanation of how I generated them is here.

We haven’t seen this before in roll call-based ideal point estimates, and I don’t think I’ve seen it before in previous years’ survey estimates (this is something I need to go back and check). So this could be something new under the political sun.

What could be causing this? Perhaps new electoral forces like the Tea Party on the right and Occupy Wall Street on the left are forcing candidates to pay lip service to dogma in some new way. And what happens after the election? Will this internal schism go away? Or does this presage a new battle between liberal liberals and liberal moderates, and between conservative conservatives and conservative moderates?

Your guess is as good as mine, though. Any ideas?

 

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