I’m not surprised Donald Trump would make this argument ; I’m surprised it took him so long to get to this point.

“The Republican Party is the party of Abraham Lincoln. Not bad,” said Trump, speaking at a rally in the Seattle suburb of Everett. “Not bad. It’s also the party of freedom, equality and opportunity.” “It is the Democratic Party that is the party of slavery, the party of Jim Crow and the party of opposition,” Trump said, drawing boos from the supportive crowd, which was heavily white.

As the Washington Post’s report noted, Trump was reading from prepared remarks, which sometimes gives him trouble: his mention of “party of opposition,” for example, was supposed to be “part of oppression.”

Nevertheless, it was only a matter of time before Trump, more pundit than candidate, adopted one of the more popular historical arguments embraced by conservative commentators.

Unfortunately for the Republican presidential nominee, it’s a point he doesn’t seem to understand especially well.

As regular readers know, we usually revisit this story about once a year, and in light of Trump’s rhetoric in Washington last night, now is as good a time as any to set the record straight once more.

The Democratic Party, in the first half of the 20th century, was home to two broad, competing constituencies: southern whites with abhorrent views on race, and white progressives and African Americans in the north, who sought to advance the cause of civil rights. The party struggled with this conflict for years, before ultimately siding with an inclusive, liberal agenda.

The result was a dramatic shift in both parties. After “Dixiecrats” began their exodus in 1948, and in the wake of LBJ signing the Civil Rights Act in 1964, the Republican Party welcomed segregationists who no longer felt comfortable in the Democratic Party. Indeed, in 1964, Republican presidential nominee Barry Goldwater boasted of his opposition to the Civil Rights Act, and made it part of his platform.

It was right around this time when figures like Jesse Helms and Strom Thurmond made the transition – leaving the progressive, diverse, tolerant Democratic Party for the conservative GOP.

In the years that followed, Democrats embraced their role as the party of inclusion, while Republicans became the party of the “Southern Strategy,” opposition to affirmative action, campaigns based on race-baiting, vote-caging, discriminatory voter-ID laws, and politicians like Helms, Thurmond, and others.

To be sure, Trump’s surface-level understanding of history isn’t entirely wrong: Southern Democrats were, for generations after the Civil War, on the wrong side of the issue. Practically all of the major segregationists of that era were Dixiecrats.

The problem, however, is with the relevance of the observation. Which matters more in contemporary politics: that segregationists were Southern Democrats or that segregationists made a new home in the Republican Party in the latter half of the 20th century?

Democrats have no reason to ignore this or sweep history under the rug: they eventually got it right, and dispatched the segregationists to the GOP, which welcomed them in the party fold.