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Evan Horowitz | Quick Study

Lacking conservatives, Legislature skews liberal

Mass. Legislature is 2d-most liberal in the land

Massachusetts has the second-most liberal Legislature in the country, behind California, according to the latest figures put together by political scientists at Georgetown and Princeton universities.

It’s not that Massachusetts Democrats are particularly left wing. Relative to legislators in a number of other states, they’re fairly moderate. In New York and Vermont, the Democratic caucuses lean further left, and the same is true in a handful of redder states, like Arizona and Wisconsin.

The reason Massachusetts ranks so high on the list of liberal legislatures is that there are almost no conservative members. Not only do Democrats control about 80 percent of both houses, but the few Republicans who do hold seats are pretty centrist. They have roughly the same political preferences as Democrats in Oklahoma, and they’re actually further left than Democrats in Arkansas.


And given this arrangement — with Massachusetts’ Republican legislators planted firmly in the center and Democrats not stretching too far left — there is relatively little polarization in the state. For now, Massachusetts seems to have avoided the fractious trend that is making politics more divisive in virtually every other state.

The rankings were put together by two political scientists, Boris Shor at Georgetown and Nolan McCarty at Princeton.

Massachusetts has the second most liberal legislature in the U.S.

Only in California do legislators lean further left.

In Massachusetts, Democrats and Republicans are not nearly as divided as the increasingly polarized parties in many other states.

Democratic legislators in Massachusetts are actually less progressive than you find in some redder states, like Arizona and Wisconsin.

However, Republicans legislators in Massachusetts are more liberal than Republicans in any other state—and farther left than Democrats in Arkansas.

Their basic approach involved two steps: compiling a huge collection of roll call votes in state legislatures, and then turning those roll call votes into information about where legislators fit in the left-right divide, which you can do if you pay close attention to when individual legislators vote together and when they split apart.

This method has produced some striking results in other areas, including tracking the growing polarization in Congress and the conservative drift of the Supreme Court.

Thanks to a nationwide survey of state legislators, Shor and McCarty are able to take their voting data from the 50 states and make comparisons between legislators on different sides of the country, ultimately teasing out the political leanings of all 99 legislative chambers (Nebraska has a single-chamber system).


One limitation of this dataset is that the information about the Massachusetts Senate is slightly out of date, having been culled from 2008. This is unlikely to make a difference in the overall estimates, given the absence of any dramatic change, like a shift of control from one party to the other.

Part of the beauty of how the research defines liberal and conservative is that it doesn’t require a rigorous account of differing beliefs. You just have to follow the votes.

Think of it like a puzzle, only you’re filling in the political spectrum. Legislators who often vote together fit side by side because presumably they have similar beliefs. Those who consistently cast differing votes get put on opposite sides.

Complete this process in a mathematically rigorous way and the finished puzzle mirrors conventional notions of left and right, with liberal Democrats on one side and conservative Republicans on the other.

Strictly speaking, then, this dataset doesn’t show that Massachusetts legislators hold a particularly liberal set of beliefs.

Rather, it shows that they support the types of policies that are embraced by California and Connecticut, contested in much of the country, and anathema in Oklahoma and Missouri. That, by itself, turns out to be a pretty good definition of liberalism.

The data show that the Massachusetts Legislature really does reflect public opinion. Bay Staters are among the most liberal people in the country, so it makes sense that they tend to elect fairly liberal legislators.


Elsewhere, this relationship seems to have broken down. Even though Coloradans and Pennsylvanians have pretty similar political views, they have very different legislatures. Colorado’s is quite liberal, Pennsylvania’s fairly conservative.

Perhaps what’s most unusual about Massachusetts, though, is that it manages to be very liberal without being too polarized.

This is different from California, for instance, where the parties are extremely far apart. Not only does California have the most liberal Democrats, it also has the second-most-conservative Republicans.

And California is far from unique in this regard. Since the mid-1990s, nearly every state has seen some increase in legislative polarization, 45 out of 50.

Some states have seen an explosion, particularly states across the West.

Massachusetts has been largely insulated from this fate, but there’s no guarantee this will last. The national trend suggests it’s hard for states to avoid falling into a more divisive brand of politics.

Evan Horowitz digs through data to find information that illuminates the policy issues facing Massachusetts and the U.S. He can be reached at evan.horowitz@globe.com. Follow him on Twitter @GlobeHorowitz