Donald Trump’s recent failed attempt to surprise the political world with a sizable group endorsement by black ministers occasioned a very sharp observation from Joy Reid on The Last Word. After Jonathan Allen noted that Trump was desperately looking for “a racial or ethnic or any other type of minority that he can go to and not already have basically poisoned the well,” Reid helpfully clarified the why of it all: “Republican primary, that’s not about black and Latin voters, because there really aren’t any in the Republican primary,” Reid said. “That’s about white suburban voters who want permission to go with Donald Trump.”

Trump’s situation is anything but unique—it’s just a bit more raw than it is with other Republicans. Ever since the 1960s, as Richard Nixon’s Southern Strategy was being born, there’s been a ongoing dilemma (if not huge contradiction) for the erstwhile “Party of Lincoln” to manage: how to pander just enough to get the racist votes they need, without making it too difficult to deny that’s precisely what they’re doing.

There are a multitude of cover stories involved in facilitating this two-faced strategy, but one of the big-picture ways it gets covered is with a blanket denial: It wasn’t Nixon’s race-based Southern Strategy that got the GOP its current hammerlock on the South, it was something else entirely. Say, the South’s growing affluence, perhaps, or its “principled small-government conservatism,” or the increased “leftism” of the Democratic Party on “social issues”—anything, really, except racial animus. Anything but that. (It’s akin to the widespread beliefs that the Civil War wasn’t fought over slavery, or that the Confederate flag is just a symbol of “Southern pride.”)

Most who make such arguments are simply mired in denial, or worse, but there are several lines of argument seemingly based on objective data in the academic literature. But a new National Bureau of Economic Research working paper that Sean McElwee recently referred to should put an end to all that.

“Why did the Democrats Lose the South? Bringing New Data to an Old Debate,” by Ilyana Kuziemko and Ebonya Washington, does three key things: First, it uses previously overlooked data—matching presidential approval against media coverage linking President Kennedy to civil rights—to shed light on a key transition period—broadly, from 1961-1963, narrowly, the spring of 1963—when the Democratic Party clearly emerged as the party of civil rights. Second, it uses another new source of data—responses to the “black president question” (first asked by Gallup in 1958), whether someone would support a black (originally “negro”) candidate for president, if nominated by their party—as a measure of “racial conservatism” to analyze the contrast between the pre- and post-transition periods.

As McElwee reported, the paper “find[s] that racism can explain almost all of the decline of Southern white support for Democrats between 1958 and 2000.” Indeed, it explains all of the decline from 1958 to 1980, and 77% of the decline through 2000. (The authors prefer the 1958-1980 time-frame, since Jesse Jackson’s candidacy in 1984 and 1988 “may have transformed the black president item from a hypothetical question to a referendum on a particular individual.”) Third, the paper looks at the other explanations—the cover stories—and finds they have only a marginal impact, at best. (Although its focus is Southern realignment away from the Democratic Party, the GOP has obviously been gaining strength at the same time as a direct result.) It also sheds light on an early phase of dealignment, starting when Truman first came out for civil rights in 1948, leading to the Dixiecrat revolt.

Before turning to the paper itself, I want to recall a point I made last year: so-called “principled conservatism” is itself heavily determined by anti-black attitudes. Southern racial conservatives had been closely tied to the Democratic Party for generations before Truman came out for civil rights in 1948, but the 1960s stand out as a decisive turning point. Among other things, I pointed out (a) that George Wallace himself had disavowed explicit racism by the end of 1963, turning to a classic articulation of anti-government/anti-“elite” conservative themes, (b) that there are both international and U.S. data showing that welfare state support declines as minority populations increase, and (c) that even attitudes related to spending to fight global warming are strongly influenced by anti-black stereotypes.

With all that in mind, there’s no reason at all to assume that any form of conservatism in America can be separated from white supremacism. We can pretend otherwise for the sake of running thought experiments, data-analysis, etc. and there can be some value is doing this—or I wouldn’t find this paper so important. But we should never forget the larger reality: we are not operating in blank-slate situation, where all hypothesis may be considered equally, in abstract purity. White supremacy is the default condition for everything in America, only the strength and salience of its impact varies from situation to situation.

Keeping all that in mind, let’s now turn to the important lessons this new paper has to tell us. As I said, it does three key things—sheds light on the 1961-1963 transition period, contrasts the pre- and post-transition periods to show the overwhelming impact of race, and examines other explanations, finding their impacts to be marginal, at best. The second of these is key, but is only possible as a result of identifying the transition point, which is crucial to making sense of everything else—both the central role of race, as well as the relative insignificance of other factors.

As the authors note, there are plausible reasons to consider alternative explanations—dealignment took a long time, but civil rights only briefly registered as the top issue, in contrast, the South’s economic gains were more gradual, better matching the gradual shift away from the Democratic Party. But what’s missing from those arguments is a full range of data on racial attitudes, particularly straddling the transition period when the Democrats emerged as the party of civil rights. The authors note that “those authors using the cumulative ANES [American National Election Survey] to address the role of racial views on party alignment typically begin their analysis in the 1970s, well after the Civil Rights and Voting Rights Acts.” Thus, they’re entering the picture very late in the game.

Building a strong case for factors other than race based on data that excludes the 1960s is like the old joke about the drunk looking for his car keys under a streetlamp, where “the light is better” rather than in the darkness up the street, where he dropped them. What sets this study apart is the uncovering of a new light source to shine into that darkness, and the excellent use that is made of that new light.

Informally, qualitatively, historians and others clearly understand when the Democrats emerged as the party of civil rights—it happened in the early 1960s, when first Kennedy, then Johnson, allied with the Civil Rights movement, introducing and passing both the Civil Rights Act of 1964 and the Voting Rights Act of 1965. The significance of this alliance was dramatically visible in the presidential election map of 1964, when Barry Goldwater—who voted against the Civil Rights Act—lost every state in the nation outside of his native Arizona, except for five Deep South states, all but one of which had gone Democratic just eight years earlier, when Dwight Eisenhower had swept almost all the rest of the country. The electoral maps of 1956 and 1964 are almost mirror images of one another, a dramatic reversal unique in American history, and a stark indication that the transition the authors are looking for took place before the 1964 election.

The authors begin their effort to nail down this transition time by turning to questions a about support for school integration in the ANES. Although different wording is used in 1960 compared to 1964 and 1968, the sense remains constant. They find that “in 1960, only 13% of Southern whites see the Democrats as the party pushing for school integration, 22% say Republicans, and the rest see no difference. Non-Southern whites see essentially no difference between the parties.” But four year later, a dramatic shift has taken place. “By 1964, 45% of Southern whites now see the Democrats as more aggressive on promoting school integration, whereas the share seeing Republicans as more aggressive has fallen to 16%. Non-Southerners’ assessment shifts similarly. The large gap in voters’ perception of the parties on school integration that emerges in 1964 holds steady in 1968.”

With the 1960/1964 window to start with, the authors then look for when that change might have occurred, using two data sources—Gallup poll measures of presidential approval, and media mentions associating the president with civil rights, both based on the fact that presidents do so much to influence the perception of their parties. They focus primarily on the New York Times, supplemented by looking at two Southern papers as well—the Dallas Morning News and the New Orleans Times-Picayune. They note “two short-lived spikes” of media mentions when Kennedy’s administration intervened in support of activists in 1961 and 1962, but a steep increase begins in May 1963, as Birmingham becomes the focus of national attention, eventually leading to mass arrests—including schoolchildren as young as grade school, along with mass beatings and the use of firehoses and dogs against protesters…all broadcast live on national TV—Martin Luther King’s “Letter from Birmingham Jail,” the eventual involvement of Attorney General Robert Kennedy, and finally President Kennedy’s televised address proposing a legislative end segregation, what would eventually become the Civil Rights Act of 1964. The NYT article count peaks in mid-June, but remains elevated above its pre-April levels through the rest of Kennedy’s presidency. Similar patterns are seen in the other papers as well.

The authors then compare this media coverage with the presidential approval levels, and find that Kennedy’s approval plummeted dramatically as he took up civil rights, but only in the white South:

The most striking result is the 35 percentage point drop in his support among whites in the South (compared to no change among other whites and a rise among all blacks) between the April 6th and June 23rd 1963 Gallup polls (which correspond to a surge of articles covering Kennedy’s support of protesters during Martin Luther King’s Birmingham campaign in May and the president’s televised proposal of the Civil Rights Bill on June 11th). Smaller Civil Rights moments (e.g., the integration of Ole Miss in September 1962) also match up to significant dips in Kennedy’s relative approval among Southern whites.

Testing the significance of other events and issues “news regarding Cuba, the Soviet Union, Social Security, etc.” does not diminish the “overwhelming explanatory power” that civil rights has in predicting his white Southern drop in popularity.

Later in the paper, the authors also look at polling match-ups of Kennedy vs. Goldwater, which began in February 1963. They note strikingly similar results:

During our key period of the spring of 1963, Kennedy goes from having a healthy, thirty percentage point lead over Goldwater to being thirty points behind him. White non-Southerners remain rather aloof toward Goldwater…. The result from the presidential match-ups suggests that Kennedy’s decline in approval documented in the previous subsection did not reflect mere short term annoyance. Within months of Kennedy’s association with civil rights, half of his Southern white supporters shifted their backing to a candidate who was from a party they had shunned for a century but who was not believed to support civil rights.

Thus, they not only identify a very narrow window in time when the Southern perception of the Democratic Party changed dramatically, they also show the specific actions involved. There is no mystery about what precipitated Southern antipathy. No guesswork required. It’s noteworthy that this shift came before the Civil Rights Act was actually passed. With these dates firmly established via the Gallup presidential approval poll, the dates of the pre-transition and post-transition period are set, and the rest of the analysis can proceed.

The heart of the paper is a “triple-difference analysis,” a regression model analysis designed to show “how much of the [1] pre- versus post-period decrease in Democratic party identification [2] among Southern versus other whites is explained by [3] the differential decline among those Southerners with conservative racial attitudes?” The design of this analysis—including the identification of a clear-cut transition point—brings the question of race’s role sharply into focus, in a way that other work, using only more recent data, simply cannot hope to match.

While the transition in the perception of the national Democratic Party took place over just a few months, there was a much longer gap between polls asking the black president question, but it’s crystal clear how significant this transition period was:

In the South, conservative racial views strongly predict Democratic identification in the pre-period, but this correlation is wiped out between August 1961 and August 1963 (the last poll of the pre- and the first poll of the post-period, respectively).

As for whites outside the South:

We find that racial attitudes have little if any explanatory power for non-Southern whites’ party identification in either period.