The rise of Donald Trump baffled many Republicans. His appeal to the part of the Republican Party that GOP leaders treat with kitchen gloves and a face mask — the voters that poke and prod candidates to death with their ever more stringent question: "Is he a conservative? A true conservative?" — seemed inexplicable. And how could a campaign run on the same nationalist themes that animated the unsuccessful Pat Buchanan campaign 20 years ago suddenly have so much force and life? Instead of talking about the interest of job-creators, the presumptive Republican nominee is talking about interest in jobs, full stop. Instead of castigating 47 percent of the country as "takers," he is advertising his paternalistic instincts to "take care" of the nation's people. The party that fought unions to pass NAFTA now is led by a free-trade skeptic.

What happened?

There are a lot of answers. First, there's always been a large section of the Republican Party that had very little knowledge or interest in conservative ideas and ideology. Second, the dropping financial and psychological costs of migration for the migrants themselves mean that questions about immigration, membership in society, and borders will begin to re-order politics around the globe in the same the way trade and open sea lanes reoriented them during the industrial revolution. Third, it did always seem odd that American politics did not have a more nationalist edge, which one analyst back in the Buchanan campaign believed could change American politics.

But perhaps American nationalism wasn't hidden away after Buchanan wore a hard-hat in New Hampshire. In fact, looking back, there were signs everywhere of it getting ready to burst out.

Just look at conservative literature. Ann Coulter's immigration-restrictionist book Adios America has been credited with altering American politics after it crossed by Donald Trump's eyes. But it had precursors.

During the Bush years, a diverse group of right-leaning writers and thinkers began sounding an alarm about what mass immigration meant for the rest of the country. Many of them emerged from California, exactly where migration's transformational effects were first known. They remembered the 1960s and '70s version of the state, when it seemed like an egalitarian and middle-class utopia, each family in a pleasant bungalow and a school system that was the envy of the world. This paradise was upended by mass immigration and galloping inequalities. And its inheritors were hungry for someone, anyone, to put into words what they were feeling.

Along came Victor David Hanson and his 2003 book Mexifornia: A State of Becoming, which posited that Mexicans fled the dysfunctional statism of Mexico but ended up recreating it in California. Another California writer, Steve Sailer, wrote blog items and articles that seemed to exercise a kind of subliminal influence across much of the right in that decade. One could detect his influence even in the places where his controversial writing on race was decidedly unwelcome. Another Californian writer, Mickey Kaus, became one of the few centrist to liberal-leaning opponents of lax immigration.

There were also national pundits like Michelle Malkin, who put a national security spin on the issue in her 2002 book Invasion: How America Still Welcomes Terrorists, Criminals, And Other Foreign Menaces To Our Shores. And there were policy wonks like Mark Krikorian, who is president for the Center for Immigration Studies and wrote The New Case Against Immigration Both Legal and Illegal in 2006.

Popular political titles like these found a large, hungry audience — and upended national politics. They drove conservative activists to shut down the congressional switchboards when President Bush tried to pass comprehensive immigration reform in his second term. They drove the founding of the militia group the Minutemen. And they drove the somewhat radical congressional candidacy of Randy Graf in Arizona.

The truth was, the great wave of migration America experienced from the early '90s to the middle of last decade was a history-shaping event with long-term consequences. But because it was hardly debated by official Washington, the passions it generated tended to find sensationalistic or conspiratorial outlets.

And immigration went hand in hand with anxiety about American jobs and sovereignty. There was a minor nationalist panic during the Bush presidency, with conspiracies floating around that North American governments would create a common currency, the Amero, in imitation of the European Union. Pictures of the currency still float around the internet today. They came with the theory that America would stave off bankruptcy by uniting itself with Canada's natural resources and Mexico's underpaid labor. With that done, an enormous new transportation network would spread across the map like a squid, the NAFTA superhighway system. The rumors were fueled by quixotic lobbying dreams. But the opposition was real and fierce, and it eventually took down the very real Trans-Texas Corridor project with it.

In other words, there were signs of an emerging Trumpism on the right for years. These political tremors were ignored during the Bush years as the GOP immolated itself on foreign policy. And so no one wanted to believe an earthquake like this was coming.

Editor's note: A previous version of this article misstated a book's publication date. It has since been corrected. We regret the error.