Category Archives: Polarization

Updated Polarization Plot for 2015-2016

We plan to update our publicly accessible data to include the results of the 2014 election.

In the meantime, here is how the states stack up in terms of polarization. One big change has been the vast increase in polarization in Colorado, which nearly matches California’s polarization. Other rapidly polarizing states include Arizona, Texas, and Missouri.

average_polarization_2015.png

June 2015 Update to Shor-McCarty State Legislatures Data

Today I posted the individual, legislator-level ideology data as well as the aggregate state and chamber-level data for our state legislature ideology data. The data is free for public download and use. Please cite our data and paper if you use this in your academic work, and/or link back to us in other work.

We have extended the data collection through 2014, and we now have 20,783 unique state legislators in our data, as well as 1,816 chamber-years of aggregate data.

As with previous iterations, we have continued to spend a lot of time and effort cleaning up the data; there should be far fewer noise-related issues. But please let us know if you see particular problems.

You can find the individual data here and the state level data here.

Bugs should be reported to us.

The roll call data collection in this update has been supported financially by the Laura and John Arnold Foundation.

State Legislative Ideology and Polarization in 2013-14

Today we posted the July 2014 update to our state legislative aggregate ideology data. One of the major features to this data release has been the incorporation of much more current roll call (1993-2013) and candidate survey (1996-2014) data. All in all, we have added about 25% more chamber-years of data.

Here’s a look at the average legislative ideology  nearly all 50 states that we have data on in 2013-2014 (the data is from 2013 but nearly all states have elections in even-numbered years, hence the data apply to 2014 as well). Higher numbers are more conservative, lower numbers are more liberal. In 2013, Oklahoma had the most conservative state legislature, followed by Arkansas, Tennessee, and Idaho. If Congress were a state, 18 states would be more conservative than it!

New York was the most liberal state legislature in the country, followed by Connecticut, California, Vermont, and Hawaii.

average_ideology_2013

And the equivalent plot for polarization in 2013.

California, once again, leads the country in the ideological divide between the Republican and Democratic parties. Colorado and Arizona are close behind, gaining ground over time.

At the other end, Rhode Island, Arkansas, and Louisiana represent the least polarized legislatures. Note that Nebraska is not in this group. This is despite the fact that the Unicameral is officially nonpartisan in its organization and elections. Nebraska’s hidden parties are polarizing quite quickly.

average_polarization_2013

 

Asymmetric Polarization in the State Legislatures? Yes and No

Last week I showed how American state legislatures are largely polarizing over the past 15 years or so; the parties are getting ever more extreme and distant from each other, above and beyond the levels of the past. I ended that post with a question: “But which parties are driving this polarization at the state level? Are both parties at fault, or is one becoming more extreme compared to the other? That is, is state legislative polarization symmetric or asymmetric?” I will tackle this subject in my this post.

When we look at Congress over the past 20 years, we can clearly see that–in both the US House and Senate–the Republican party has gotten more extreme over time relative to the Democrats (though in the House Democrats have polarized to a smaller degree as well). This is a familiar story of asymmetric polarization. In fairness, Democrats’ move in the liberal direction started earlier than Republicans: the 1940s versus the mid 1970s. Still, in recent years, Congressional Republicans have unquestionably moved further, faster.

party_chamber_years_congress_cs

The data and method that Nolan McCarty and I have developed shed light on trends in America’s state legislatures. Let’s look at the picture graphically, plotting party medians over time, separately for each chamber (click on the graphic for a higher-resolution version). By convention, more positive scores represent more conservative preferences, and more negative scores represent liberal preferences.

party_chamber_years

Looking across the states, Republicans on the whole are clearly polarizing faster than Democrats. In 57 of the 99 state legislative chambers, they are getting more conservative over time, while in 47 chambers Democrats are getting more liberal. In 26 chambers Democrats are actually getting more conservative (eg, depolarizing), while the converse is true in 20 chambers for Republicans where they are getting more liberal. In 26 chambers Democrats are roughly stable and the same is true in 22 chambers for Republicans.

But what the data clearly reveal is that states are wildly diverse. In some states like Tennessee and Colorado, Republicans are getting more extreme in recent time, while Democrats are not changing much. But in other states like Idaho, Mississippi, and California, it is Democrats who are largely responsible for the states’ recent polarization. And finally, there are states like Texas, Missouri, and Nebraska where both parties are polarizing roughly equally and simultaneously.

So the polarization story is similar in some ways in state legislatures than in Congress: Republicans are leading the charge to the ideological poles on average. But it’s different, too: the average story obscures lots of differences across states. State polarization trends thus underline the usefulness of studying state legislatures as a laboratory for political observers: there’s just lots of variation to work with in trying to understand what causes what. And so we should look to state experiences to see whether reforms in areas like redistricting, primaries, campaign finance, and so on do anything to mitigate polarization, and whether some reforms might have unintended consequences that make it worse.

 

Polarization Trends in American State Legislatures by Chamber

The political parties in Congress are increasingly polarized in ideological terms. This is largely driven by replacement rather than adaptation; that is, moderates are increasingly leaving Congress, and being replaced by ideological extremists.

The plot below shows the difference between the Republican and Democratic party medians using Poole et al’s common space NOMINATE scores, for the 103rd (1992-1993) through the 112th (2011-2012) Congresses. Under this common measure, a larger gap between the centers of both parties indicates a greater level of polarization.polarization_congress_years_cs

Both House and Senate are polarized (the distance is greater than zero), and they are getting more so over time. The US House in particular is both more polarized in terms of level and polarizing faster in terms of trend relative to the US Senate.

What about American state legislatures? It’s important to nail down these numbers because we need to know where we stand to find out if polarization is leading to political gridlock and dysfunctional policy. We also need a barometer of polarization to find out whether reforms like opening up primaries, taking redistricting away from politicians themselves, term limits, and so forth can do anything about this yawning gap between the parties. And since there are 50 state legislatures, we might find answers to these questions more quickly and definitively than we can with Congress, of which we only have one.

Earlier in this blog I showed evidence that most state legislatures are in fact quite polarized, and a significant number of them are even more polarized than Congress. The data underlying these figures can be found here, and the paper explaining how Nolan McCarty and I came up with the numbers can be found hereNow we’ll take a more detailed look at the state polarization trends for all 50 states over time. The plot below shows the distances between the party medians for all 50 states over approximately the same time period, roughly 1996-2010.

polarization_chamber_years

As with the US Congress, all 99 state legislative chambers (Nebraska has a single chamber commonly referred to as the Unicam, which I term a Senate here) are polarized. In 59 of those 99 chambers, the parties are getting more distant from each other. In 16 of them, the parties are actually depolarizing or getting closer. Finally, in 24 chambers, the parties are roughly stable in relation to each other.

However, in most states, unlike in the US Congress, the upper (Senate) chamber is typically more polarized than the lower (House or Assembly) chamber. On the other hand, the lower chamber is polarizing faster in more states than the upper chamber. It is not yet clear why these differences should exist.

The top 10 fastest polarizing chambers, in order, are the Idaho Senate and House, the Missouri Senate, the Arizona Senate, the Hawaii Senate, the Colorado Senate, the Tennessee House, the Nevada Senate, the Maryland Senate, and Mississippi Senate.

At the same time, California retains its title as the most polarized state legislature in the country. It has even managed to move up a couple of notches in the past 15 years. 

Another notable state is Nebraska, whose Unicam is amongst the fastest polarizers in the country, despite the fact that it is nonpartisan by law in the chambers and at the voting booth. Seth Masket and I show in a paper how parties in the state have overcome this powerful prohibition to work as cohesive, disciplined units–just like other states.

But which parties are driving this polarization at the state level? Are both parties at fault, or is one becoming more extreme compared to the other? That is, is state legislative polarization symmetric or asymmetric? I will tackle this subject in my next post.

Interestingly enough, a few state chambers are actually depolarizing: the parties are actually coming closer together. The fastest depolarizing state chambers, in order, are the Wyoming House, the Oregon Senate, the Alaska Senate, the Ohio Senate, and the North Carolina Senate. This is completely unheard of in recent years in Congress.

NB: The scales of the two plots aren’t comparable because they are taken from two separate data sources. However, in technical terms, they are both common space measures which disallow individual legislator ideological drift in order to facilitate an apples-to-apples comparison.

State Legislatures and Polarization

America’s state legislatures are polarized–just like Congress–between liberals and conservatives, Democrats and Republicans. That polarization creates gridlock, when it’s difficult to get legislation passed and policy problems addressed.

But just how polarized are they? We haven’t been able to tell in the past, because we haven’t been able to determine just how liberal or conservative state legislators are in all 50 states. One major reason why is that each state in its own way is rather unique. Massachusetts Republicans aren’t the same as Texas Republicans; the same is true for each state’s Democrats. Nor do they vote on the same things. These immutable differences mean that measuring  ideology–and levels of polarization–in state legislatures is much more difficult than that for Congress.

Nolan McCarty (Princeton University) and I wrote an academic paper in 2011 that explained our method for overcoming this problem. We have been working diligently since then to update our data, which we have released for free to the scholarly community and public here.

With our aggregate data in hand (and updated from our original estimates), we can begin to make precise comparisons between the states and Congress on a number of dimensions, including polarization. The plot below summarizes our measures for legislative polarization, averaging across all the years of our data (approximately 1996-2008), and across both legislative chambers (except for Nebraska).

The horizontal axis measures the amount of polarization, defined as the average ideological distance between the median of the Democratic and Republican parties in the state legislative chambers; larger numbers indicate more division. The dashed line is the level of Congressional polarization, included as a comparison (“US”).

state_polarization_mcmc_1996-2011

What becomes immediately obvious is how different the states are from each other–and Congress–in terms of polarization. Some states, like Louisiana and Rhode Island, have quite unpolarized state legislatures. In Louisiana, both parties are fairly conservative, and in Rhode Island, they are both fairly liberal.

The state that sticks out like a sore thumb is my current home state, California. It is incredibly polarized; Democrats are extremely liberal, and Republicans are extremely conservative. In fact, California’s polarization is considerably larger than that in Congress (unlike Congress, however, Democrats dominate the state so thoroughly that this polarization is becoming increasingly toothless). This is also true for a number of other states.

All in all, polarization varies fairly dramatically across states.  The natural question is: why? Nolan McCarty and I–along with some coauthors–are engaged in a number of different research projects to try to answer that very question, as are a number of other scholars.

NB: We can measure Nebraska’s distance between party medians because, despite the fact that the Unicameral is officially nonpartisan, party affiliations of legislators are unofficially well known. We used friend and coauthor Seth Masket’s excellent Nebraska party data for that purpose.