To the ears of politically engaged North Carolinians, it may sound strange to hear claims that changes in partisan control don’t yield significant changes in state policy. But among scholars, this has been a widespread view for many decades.

It seems completely inconsistent with what’s happened in our state since 2010, when Republicans won control of the legislature and began implementing tax cuts, regulatory reform, school choice, and other policies they’ve long championed. Both the fury of progressives and the pride of conservatives suggest that North Carolina’s rightward turn must have been significant.

The old “parties don’t matter” hypothesis wasn’t ridiculous, however. Its adherents offered two reasonable justifications for the claim, each based on empirical evidence.

One was that while politicians clearly bring philosophical principles and agendas to their legislative work, their overarching goal is to get reelected. That means first nailing down their party base and then attracting enough swing voters to get to a majority (or a plurality as the case may be).

Even if swing voters are scarce, their political preferences set some practical limits on what state policymakers can do. If Republicans move a state too far right, or Democrats too far left, they risk losing the next election.

The other justification for the old view was more basic: the two parties weren’t that far apart ideologically. There were conservative Democrats in Southern and Plains states and moderate-to-liberal Republicans in the Northeast and Midwest.

The parties were coalitions of interest groups and regional blocs, not political-philosophy clubs. You couldn’t assume that a Republican governor replacing a Democratic one in, say, New York would result in dramatic shifts in fiscal, regulatory, or education policy. You couldn’t necessarily predict which state would enact pro-union legislation based on which party controlled the legislature.

As we survey state government in North Carolina and elsewhere nearly two decades into the 21st century, the situation looks rather different. The two parties have become more ideologically coherent. When voters tune into politics, their news diet focuses more on national stories and the circus in Washington than was the case when their parents and grandparents were reading newspapers and watching TV news.

And as voters have increasingly sorted themselves into communities and states on the basis of common values and lifestyles, the scrimmage line of politics moved away from the 50-yard marker. In red states, the “median voter” shifted rightward. In blue states, the shift was leftward.

While all this was going on, the effect of partisan control on state policy outcomes was becoming more pronounced. In a 2017 paper in the Journal of Politics, three professors at the Massachusetts Institute of Technology reported the results of their study of state elections and legislative outcomes from 1936 to 2014.

“Between the 1930s and 1980s,” they found, “the partisan composition of state governments had little causal impact on the ideological orientation of state policies.” Since then, however, “partisan effects have grown dramatically.” Democratic governors and legislatures are more likely to increase spending, hike taxes, and introduce new regulations. Republican governors and legislatures push in the opposite direction.

Even within a fixed pie of state expenditures, party control now appears to shape fiscal priorities. A 2019 study published in State Politics & Policy Quarterly found that states with Democratic governments tend to spend more on redistributive programs (think Medicaid and welfare) while those with Republican governors or legislatures spend more on “developmental” programs such as infrastructure.

I saw some evidence for this recently when I looked at the share of North Carolina’s state budget devoted to transportation funding. Since the advent of competitive two-party state politics in the mid-1980s, transportation’s share has been higher when the GOP held either the governorship or legislature. It’s been lower when Democrats had unified control.

However, the gap wasn’t very large — and that’s where the old view still merits some respect. Partisanship matters more than it used to. But state policy remains inherently incremental, in large part because that’s how voters like it.

John Hood (@JohnHoodNC) is chairman of the John Locke Foundation and appears on “NC SPIN,” broadcast statewide Fridays at 7:30 p.m. and Sundays at 12:30 p.m. on UNC-TV.