Since the mid-1930s, Massachusetts has been steadfastly liberal, and Mississippi has been consistently conservative — no surprise there.
Less well known are the sharp turns to the right taken by Utah and Idaho in recent decades, and Vermont's relatively late turn to the left.
New research that details these shifts and others might also offer an explanation for Washington gridlock.
Political scientists at the Massachusetts Institute of Technology have measured for the first time the relative liberalism or conservatism of all 50 states by examining a host of policies from the past eight decades.
The study shows that state policies across the country became more liberal between the 1930s and 1970s — and then stopped. In more recent years, overall economic policies have been constant, but social policies have become more liberal.
The findings also confirmed what might have been suspected for some time: that over the past 20 years, states have become more politically polarized — not just in voting for president or members of Congress but also in state-level policies. And that if a state has conservative economic policies, for instance, that conservatism prevails across social policies as well.
In "The Dynamics of State Policy Liberalism, 1936-2014," Christopher Warshaw and Devin Caughey, assistant professors of political science at MIT, set out to produce a comprehensive look at how the political orientations of all 50 states have shifted to the left or the right between 1936 and 2014 by examining laws on 148 policy issues.
"To understand national politics, we can learn about state politics," Warshaw said in an interview.
"Basically, name a policy, and Mississippi is the most conservative state," Warshaw said. South Carolina, Georgia, Alabama, and Arkansas are the next-most conservative states. By contrast, California, Connecticut, Hawaii, Massachusetts, New York, and (perhaps surprisingly) New Jersey rank among the most liberal places in state-policy terms.
The data offer an opportunity to get a clearer picture of what can push a state's political orientation to the left or to the right, more so than just an examination of how each state voted in a presidential election, the researchers said. The study lays the groundwork for examining all kinds of factors that could influence state policy over time, such as the political affiliation of a governor, population shifts, or changes in the economy. It can also be used to measure the impact of changes in campaign finance laws or the impact of state-level lobbying by groups such as the American Legislative Exchange Council, or ALEC.
The new research also helps to indirectly explain Washington gridlock. The lack of legislative progress on major issues in Congress can be traced, at least in part, to the study's finding that state policies are becoming more polarized from state to state, said Joshua D. Clinton, political science professor at Vanderbilt University.
"I think they show really nicely something we kind of know," said Clinton, who cited the MIT study in a paper he cowrote about abortion and charter school policy. "Southern states and Northeastern states have very different sets of laws, and they're getting increasingly different."
One example of this is in the different ways Medicaid expansions were enacted in different states, and the resulting differences in access to health care, Clinton said.
When representatives are elected from more polarized environments, it makes it more difficult to work together on the national level, he said.
On the whole, states shifted to the left between the 1930s and the 1970s, as civil rights were granted and a social safety net was established. But after the 1970s, that shift ended for decades.
State government grew significantly between the 1950s and the 1980s, but that stopped under President Ronald Reagan. In the late 1970s and early '80s, the public wanted government to do less, the researchers note.
"We see that across lots of different economic policies, even social policies," Warshaw said, citing an end to the enactment of laws meant to protect women and racial minorities.
In the early 1980s, more liberal laws and policies, including an equal rights amendment for women and measures to protect the environment, went nowhere.
But in the more recent past, states have tilted leftward again, with the passage of gay rights laws, including gay marriage protections, but the change has been gradual.
The study found that since 1936, Southern states have enacted more conservative policies, while states in the Northeast and West Coast have become more liberal.
Closer to home, New England was a bastion of Republicanism until the New Deal and President Franklin Roosevelt, Warshaw said. By the 1940s and 1950s, New England was more liberal.
Massachusetts has been among the three or four most liberal states in the country every year since at least the beginning of this research period, in 1936, along with New York and California, Warshaw said.
Massachusetts' reputation as one of the country's most liberal states has been bolstered by several laws, including a ban on most age discrimination in employment in 1937, a law requiring equal pay for women in 1945, fair employment laws to address racial discrimination in the workplace in 1946, and a minimum wage for men and women in 1946.
And though Vermont has more liberal policies than most states in the modern era, recognizing civil unions and gay marriage earlier than other states, that was not always the case. In the early periods covered by the study, Vermont had stingy welfare policies, and was slow on laws protecting women in the workplace and civil rights. The Green Mountain State didn't liberalize until well into the 1960s, and didn't become one of the most liberal states until the 1990s, Warshaw said.
It's a similar story in Maine, which in 1936 was the most Republican state followed by Vermont and New Hampshire, and has only become more liberal in the last couple of decades. In 1936, Maine and Vermont were the only two states in the country that Roosevelt didn't win, but since have become more liberal, Warshaw said.
"Some of these states had big shifts over time," he said.
The policy shifts are preceded by shifts in public opinion, so if the public grows more liberal, the policies follow, he said.
Other states that got more liberal over time were states in the mid-Atlantic, such as Delaware and Maryland. They were rural in the 1900s, with no strong union or manufacturing presence, which typically contributes to a liberalizing effect.
Trending in the other direction are Utah and Idaho, which were liberal in the early 20th century but over time became more conservative.
In the South, many states have been consistently conservative since 1936. Mississippi, South Carolina, and Alabama rank as the most conservative states across time, Warshaw said, no matter whether the issue is economic or social. This one-dimensionality emerged during the New Deal, though it's possible that certain states were liberal on certain issues and conservative on others before then, Warshaw said.
"Really, the South is conservative on everything, as opposed to just being conservative on race," said Caughey, study coauthor. "It has the least generous welfare policies, the most restrictive social regulations, and so on. These things we think of as being only loosely associated, when we actually look at policies, line up pretty closely."