Every few years I try to write a column staking out a reasonable middle ground on immigration. After all, most big, important issues are clashes in which both sides have a piece of the truth.

The case for restricting immigration seems superficially plausible. Over the last several decades we’ve conducted a potentially reckless experiment. The number of foreign-born Americans is at record highs, straining national cohesion, raising distrust. Maybe America should take a pause, as we did in the 1920s. After all, that pause seemed to produce the cohesive America of the 1940s that won the war and rose to pre-eminence.

Every few years I try to write this moderate column. And every few years I fail. That’s because when you wade into the evidence you find that the case for restricting immigration is pathetically weak. The only people who have less actual data on their side are the people who deny climate change.

You don’t have to rely on pointy-headed academics. Get in your car. If you start in rural New England and drive down into Appalachia or across into the Upper Midwest you will be driving through county after county with few immigrants. These rural places are often 95 percent white. These places lack the diversity restrictionists say is straining the social fabric.

Are these counties marked by high social cohesion, economic dynamism, surging wages and healthy family values? No. Quite the opposite. They are often marked by economic stagnation, social isolation, family breakdown and high opioid addiction. Charles Murray wrote a whole book, “Coming Apart,” on the social breakdown among working-class whites, many of whom live in these low immigrant areas.

One of Murray’s points is that “the feasibility of the American project has historically been based on industriousness, honesty, marriage and religiosity.” It is a blunt fact of life that, these days, immigrants show more of these virtues than the native-born. It’s not genetic. The process of immigration demands and nurtures these virtues.

Over all, America is suffering from a loss of dynamism. New business formation is down. Interstate mobility is down. Americans switch jobs less frequently and more Americans go through the day without ever leaving the house.

But these trends are largely within the native population. Immigrants provide the antidote. They start new businesses at twice the rate of nonimmigrants. Roughly 70 percent of immigrants express confidence in the American dream, compared with only 50 percent of the native-born.

Immigrants have much more traditional views on family structure than the native-born and much lower rates of out-of-wedlock births. They commit much less crime than the native-born. Roughly 1.6 percent of immigrant males between 18 and 39 wind up incarcerated compared with 3.3 percent of the native-born.

What about the rise of social distrust? Restrictionists often cite a 2007 Robert Putnam study finding that more diversity leads to less trust. But Putnam tells me they are distorting his research. He found that diversity’s benefits outweigh its disadvantages, that trust declines over the short term as places grow more diverse, but that over the long term Americans find new ways to boost social solidarity.

What about assimilation? Restrictionists argue that the melting pot is broken. But the definitive survey of the literature from the National Academies of Sciences, Engineering and Medicine finds this is not true. Most descendants of immigrants stop identifying with their ancestral homelands and simply think of themselves as white. In the 2010 census, 53 percent of Latinos identified as white, as did a similar percentage of Asian-Americans with mixed parentage.

In 1945 Germany was divided. One part went capitalist and the other went communist. After a half-century it was perfectly clear that capitalism was a more successful system than communism.

Over the past few decades America has, willy-nilly, conducted a similar experiment. About 500 counties, mostly in metro areas, have embraced diversity — attracting immigrants and supporting candidates who favor immigration. About 2,600 counties, mostly in rural areas, have not attracted immigrants, and they tend to elect candidates who oppose immigration and diversity.

The results are just as clear as in the German case. Between 2014 and 2016 the counties that embrace diversity accounted for 72 percent of the nation’s increased economic output and two-thirds of the new jobs. The approximately 85 percent of counties that support restrictionists like Donald Trump accounted for a measly 28 percent of the growth.

Republicans’ problem is that since George W. Bush left town they’ve become the East Germans of the 21st century. They have embraced a cultural model that produces low growth and low dynamism. No wonder they want to erect a wall.

Progressives say Republicans oppose immigration because of bigotry. But it’s not that simple. It’s more accurate to say restrictionists are stuck in a mono-cultural system that undermines their own values: industry, faithfulness and self-discipline. Of course they react with defensive animosity to the immigrants who out-hustle and out-build them. You’d react negatively, too, if confronted with people who are better versions of what you wish you were yourself.

<DAVID BROOKS>