Around a century ago, amid a massive surge of immigrants, Americans — themselves virtually all of foreign blood — pushed back in what turned into a more than four-decade-long uprising against newcomers.

Now, the U.S. immigrant population is nearing the same proportions, and again Americans are revolting.

Why it matters: The new wave of migration is, along with automation, one of the primary drivers behind the anti-establishment uprising roiling both the U.S. and Europe, experts say.

At 13.5% last year, the population of foreign-born U.S. residents is nearing the peak of 14.8%, reached in 1890.

of foreign-born U.S. residents is nearing the peak of 14.8%, reached in 1890. If history holds, the U.S. is entering a new, prolonged era of anti-immigrant fever.

the U.S. is entering a new, prolonged era of anti-immigrant fever. And, if so, it won't be easy to tamp down: The last time, it took the legislative mastery of Lyndon Johnson to quell the hysteria, in a bill he muscled through Congress in 1965. But now there is no Johnson.

"We've begun the 21st century as we began the 20th. The target may be different, but the anxiety is the same."

— Muzaffar Chishti, director of the Migration Policy Institute at New York University law school

The background: The U.S. has gone through waves of anti-immigrant fevers.

In the 1850s, a movement began that was anti-Catholic and anti-Irish, and it turned into the Know Nothing political party.

In the late 19th century, another wave arose against a surge of some 9 million eastern and southern Europeans.

In 1921, Congress approved the Emergency Quota Act and then the National Origins Act, which kept allowing western and northern Europeans but all but blocked almost anyone else. Asians were effectively barred.

Then, in 1965, Johnson pushed through legislation that ended the quota system. But experts say the current fever is in large part an unforeseen byproduct of that legislation: By linking immigration to relatives of the current population, Congress thought the makeup of the U.S. population would not change much. Instead, it resulted in the surge of immigrants from Latin America and elsewhere (see chart below).

Expand chart Data: IPUMS-USA, University of Minnesota (1900–2000), U.S. Census Bureau (2010, 2017); Chart: Harry Stevens/Axios

As researchers have sought an answer for the Western world's abrupt pivot to populism, the main explanations they have settled on are: