It’s essential to remember that the Southern Strategy did not originate with cynical GOP pols and right-wing extremists, but was—ironically enough—first hammered out in the pages of National Review, the very publication that now excoriates Trump “a philosophically unmoored political opportunist who would trash the broad conservative ideological consensus within the GOP.” National Review can disavow Trump as loudly as it wants, but it was the magazine—and the conservative establishment that drew its political ideas and strategies from it—that created the politics that have now morphed into Trumpism.

The racist voters swarming around Trump didn’t just pop out of nowhere. The Republicans have been courting them for decades now, in a dramatic break from the party’s origins. From its creation in 1854 in opposition to the expansion of slavery until the 1940s, the Republicans were the party of the North, and more anti-racist (albeit sometimes only marginally so) than the Democrats, whose most reliable base of support was the “solid” white South.

This pattern started breaking up in the 1930s, when Democrats began to win the votes of blacks hard hit by the Depression. Despite the compromises spawned by Franklin Roosevelt’s dependance on white Southerners, the New Deal era also saw members of his party, most notably First Lady Eleanor Roosevelt, taking a vocal stance in favor of civil rights. Roosevelt’s successor, Harry Truman—who needed the votes of Northern blacks to score his upset victory in 1948 over Thomas Dewey—was even more forthright, desegregating the military and running on the strongest civil-rights platform the Democrats had ever put forth. This immediately caused dissension in the ranks, with erstwhile Democrat Strom Thurmond of South Carolina leaving the party to run on the “Dixiecrat” ticket. But it wasn’t until 1964 that Thurmond was ready to join the Republican Party, which had to undergo its own ideological transformation before it could welcome open white supremacists.

But as the political parties were evolving, there was a fateful shift among conservative intellectuals. Prior to the 1950s, conservative thought leaders who lived outside the South had no special love for the region or for its version of apartheid. Leading right-wing writers like H.L. Mencken and Albert Jay Nock decried lynching and saw the South as a shameful backwater. One of America’s leading conservative thinkers, the German refugee Eric Voegelin, wrote a pioneering debunking of scientific racism in 1933.

That all began to change with the emergence of National Review in 1955. The magazine was launched in opposition to the moderate Republicanism of Dwight Eisenhower, who was seen as being soft on communism and all too willing to compromise with liberals. And among the policies National Review objected to was Eisenhower’s enforcement of civil rights laws. In a famous 1957 editorial written by National Review founder William F. Buckley, the magazine argued that the South “must prevail.” Is the white community in the South, the editorial asked, “entitled to take such measures as are necessary to prevail, politically and culturally, in areas in which it does not predominate numerically?” Buckley did not flinch from providing a blunt answer. “The sobering answer is Yes—the White community is so entitled because for the time being, it is the advanced race.” This position would be re-iterated by the magazine many times. In a 1960 editorial, the magazine wrote, “In the Deep South the Negroes are, by comparison with the whites, retarded.”

The stance laid out by National Review in the late 1950s and early 1960s was an innovative one. Before the magazine made Southern racism integral to right-wing ideology, Northern conservatives affiliated with the Republican Party felt no need to oppose civil-rights measures—and certainly no impetus to take the side of preserving Jim Crow segregation. Quite the reverse, in fact: Leading Republicans like Richard Nixon, eager to secure the African-American vote in the North in his 1960 race against John F. Kennedy, were competing with Democrats to be seen as civil rights champions.

Where did National Review’s sympathy for the white South stem from? In Buckley’s case, part of it was personal. The Buckley family had a plantation in South Carolina which the historian Garry Wills, who was close to Buckley in the 1950s and 1960s, wrote about in a 2009 essay in the Atlantic. “His mother was a southern belle from New Orleans whose grandfather had been a Confederate soldier at Shiloh,” Wills recalled. “She kept the attitude toward blacks of her upbringing. One time, when we were sailing and stopped at Charleston, South Carolina, Bill took me to his father’s winter home. When we arrived, we were greeted by a black retainer who had known Bill from his childhood—he called him ‘Master Billy.’ It was not surprising that Bill and I would initially disagree about the civil-rights movement.”

But beyond Buckley’s personal quirks, the magazine supported white Southern resistance to the civil rights movement for both ideological and politically strategic reasons. Fiercely anti-communist, National Review saw the civil rights movement as symptomatic of a perilous trend toward egalitarianism—one that was allied with decolonization movements around the world. In purely political terms, the Southern backlash provided an opportunity for the insurgent conservatives to latch on to a mass movement—and move the ideological profile of the GOP to the right with a new base of support. With white Southerners resenting both liberal Democrats and moderate Republicans for pushing civil rights, Buckley and his allies in the fledgling conservative movement recognized that these folks could become reliable foot soldiers to support its larger war against the left—and make it politically viable.

In the February 12, 1963, issue of National Review, the magazine’s publisher William Rusher laid out a plan for Barry Goldwater to run, and win, in 1964 by appealing to disaffected white Southerners and wresting Southern states from the Democrats’ grip. As Rusher’s biographer David Frisk notes in his 2011 biography, If Not Us, Who? William Rusher, National Review, and the Conservative Movement, “this was among the first articulation of what became known as the ‘southern strategy’ and was perhaps the most consequential, for it may have nudged Goldwater closer to a candidacy.” (Later, in 1975, Rusher would try to form a break-away right-wing populist party that would abandon the country-club Republicans. Rusher tried to recruit George Wallace for this party, which was to be aimed at white working-class conservatives. The whole effort anticipates Trumpism to a remarkable degree.)

Buoyed by the nascent conservative movement, Goldwater won the Republican nomination in 1964. Though he lost in a landslide to President Lyndon Johnson, Goldwater’s outspoken opposition to civil-rights legislation helped him carry the white vote in much of the South. Aside from his native state of Arizona, Goldwater won the popular vote in the Deep South states of Alabama, Georgia, Mississippi, Louisiana, and South Carolina, where Thurmond was his most ardent surrogate. In the process, Goldwater’s campaign also devastated the Republican Party as a competitor for the black vote, garnering only 6 percent of African-Americans nationwide. By contrast, Eisenhower had won 39 percent of the black vote in 1956, and Nixon 32 percent in 1960.

Goldwater’s Southern Strategy, inspired by National Review, set a pattern for the next half-century—and more. The party had changed so much in 1964 that even Nixon, who had been liberal on civil rights before the Goldwater takeover, adopted the Southern Strategy in 1968 and 1972. Dixie would be the new heartland for the Republican Party, which would stoke white resentment over African-American advances. As the Democratic Party became more multi-racial, winning not just black voters but also Latinos and most non-white immigrants, the Republicans remained an overwhelmingly white party.

The Southern Strategy was the original sin that made Donald Trump possible. If Republican voters were anywhere near as diverse as the Democrats’, a candidate like Trump would have been marginalized quickly. Conservative elites can denounce Trump all they want as a “cancer” or an impostor. In truth, he is their true heir, the beneficiary of the policies the party has pursued for more than half a century.

Trump does represent an innovation, or perhaps a return to form, in one way. The Southern Strategy has long relied on coded appeals to racism—an emphasis on “law and order,” denunciations of racial quotas, and so on—that enticed the bigoted base while still giving the Republican Party plausible deniability. This sort of winking racism no longer works, in part because the base feels the party hasn’t delivered. Trump’s signature trait is that he doesn’t hide his bigotry, so he excites voters who feel that here, at last, they have the real thing.

If Trump is victorious in South Carolina and the six upcoming Southern contests on Super Tuesday, he’ll owe much of his success to the racial politics crafted by the conservative movement that reshaped the Republican Party. There’s no denying that.