Being an unrepentant data nerd, I was delighted when I recently came across an incredible dataset from the boffins at the University of Chicago. Through the General Social Survey (GSS), they’ve been surveying Americans for their views on all kinds of questions—from the ethics of spanking kids to their opinions of Canadians (nothing about the ethics of spanking Canadians, though)—since 1973. Along the way, the GSS has been asking respondents about their political affiliation. This has opened the possibility of taking an empirical approach to a question I’ve been wondering about since 2016: how did this country become so politically polarized?

One line of thinking is that liberals have veered sharply to the left, opening up an ideological gap with the rest of the country. This strain of argument has long circulated within conservative media, but it’s now in full bloom in some parts of the progressive universe, too.

Here is Kevin Drum, a left-of-center journalist:

It is not conservatives who have turned American politics into a culture war battle. It is liberals. And this shouldn't come as a surprise: Almost by definition, liberals are the ones pushing for change while conservatives are merely responding to whatever liberals do. More specifically, progressives have been bragging publicly about pushing the Democratic Party leftward since at least 2004—and they've succeeded.

And Damon Linker in the The Week, an ideologically center-left magazine:

…American polarization is happening much less asymmetrically than many Democrats would like to believe — and on certain issues wrapped up with the culture war, Democrats have moved further and faster to the left than Republicans have moved to the right.

If this is what prominent liberal commentators are saying, you can imagine what the Wall Street Journal editorial board, let alone Fox news, is saying. The reality seems more complex, though.

Both parties actually agree on a lot…

Democrats haven’t suddenly veered left. They’ve been gradually moving left since we began measuring these things in the 1970s.

This is pretty common: as countries become wealthier, they tend to get more progressive—more inclusive along racial and gender lines, more protective of the natural environment, more concerned about violence—whether it’s capital punishment, police violence, or guns—and more sensitive to disparities in wealth and income. They tend to value personal freedoms more, as long as those freedoms don’t impinge on the rights of others.

What I feel is lost in a lot of political commentary is that, for the most part, this shift is happening in red America, too. The General Social Survey shows that Republicans are increasingly tolerant of recreational use of marijuana, pre-marital sex, and homosexuality. Americans of both political stripes increasingly think divorce should be easier. They both envision a more equal role for women in society, in the workforce and in politics. Across these issues, all Americans are becoming more liberal with every passing year.

…but where they disagree, they really disagree

But despite these trends, the US is deeply polarized. Why? A handful of issues have become immensely divisive—abortion, guns, the military, the environment, and race issues, in particular. The cause of the division on these issues is that Democrats have been gradually drifting leftwards while Republican thinking has stayed the same—or even shifted back to views they held decades ago.

Whether you think Republicans are regressive—or that they’re holding onto something essentially American that is slipping away—depends on your politics. But when I compare the GSS survey data of Americans with surveys from around the world, the stasis in Republican thinking is clearly unusual.

Guns N’ Roses

Take gun control, for example. 59% of Republicans oppose “a law which would require a person to obtain a police permit before he or she could buy a gun”. Red-state America has a unique, wild-west love of guns that simply isn’t found elsewhere. This makes international comparisons difficult. But perhaps the closest parallel is just across the border, in the Canadian province of Alberta (the ‘Texas of the North’). In a country that overwhelmingly supports tighter gun control, Alberta has always been a holdout. Yet, polls show that even in Alberta, 56%—ie, a similar proportion as Republicans who oppose a permit requirement—want handguns banned outright.

Or take environmental issues: only 49% of Republicans support additional government expenditure to protect the environment. This is 23% lower than three decades ago. For most European countries, that figure is between 60% and 80%—and rising.

Abortion is one of the largest wedge issues in the US. 62% of Democrats support a woman’s right to choose to have an abortion for any reason, versus only 29% of Republicans. International comparisons are again tricky here, since people tend to oppose abortion on religious grounds, and most countries which are comparable to the US in terms of wealth and other factors are much less religious. Still, let’s look at some of the wealthier countries in Latin America, since they at least share religiosity with American Republicans. Amongst these, Mexico is the most religious, and the most opposed to abortion. Yet, surveys show that support for legalized abortion stands at 59% in Mexico (twice as high as in the US amongst Republicans). Across Latin America, support for legalized abortion has risen by 10-15% over the last ten years—the same amount by which it’s fallen over the same time period, in the US, amongst Republicans.

It started in the ‘90s

The steadiness of Republican opinion on these issues is not just unusual in comparison with Democrats, or in an international context—it’s also out of step with the trends in this country before 1993.

From 1973 until 1993, both parties grew more liberal, even on the issues which are ideological battlegrounds today. Then, in 1993, something changed: Democrats continued liberalizing (following global trends), and so did Republicans on some issues, but not all of them.

The National Review commentator William F Buckley said the role of the Conservative is to “stand athwart history, yelling stop”. The data shows that on certain issues—especially abortion, guns, the military, the environment, and race—Republicans yelled stop sometime in the early ‘90s. Democrats kept going. That seems to be one explanation for why we are so polarized today.