The Republican Party has become the Southern Party. Or so we’ve been told ad nauseam, at least since Richard Nixon launched an effort wean disaffected whites from the Democratic Party. There’s more debate about the chronology and causes of the South’s realignment than many people realize: the wonderfully named Sean Trende argues that it began long before 1968 and had more to do with urbanization than than with race. For some critics, however, the electoral map is irrefutable evidence that the Party of Lincoln has become the Party of the Confederacy (plus the mountain West, which no one ever talks about).

But it may not always be that way. As the outcomes in 2008 and 2012 showed, the Upper  South is much more competitive than it used to be. Virginia leans blue. And North Carolina is up for grabs.

Larry Sabato offers an intuitive but nevertheless interesting explanation of what’s going on (h/t @jbouie). Using data from the 2010 census, Sabato observes that states that have experienced big declines in the number of voters who were born there (the “nativity rate”) tend to turn blue. That’s largely because minorities, whether from foreign countries or other states, are more likely to move than whites. They are also more likely to be Democrats.

Virginia, whose population has also been transformed by the growth of the affluent D.C. area, has been the pioneer of this change. North Carolina is following a similar pattern. Based on current trends, Georgia’s nativity rate is likely to drop below 50 percent within the next decade or so. If that happens, and if Sabato’s right, it may again become possible for Democratic presidential candidates to win there too.

The loss of the Upper and Coastal South would be bad news for Republicans. On the other hand, the correlation between high nativity rates and support for the GOP means that the Republican stronghold may be shifting to the Midwest, which attracts few new residents but still commands a pile of electoral votes.

Consider the irony of such a scenario. Republicans have lost ground in North and gained it in the South partly because their appeal is concentrated among whites. But the South is becoming far less white than it used to be, partly because of immigration and partly because its weather and lower cost of living have made it an attractive destination for domestic relocation. As a result, Republicans are beginning to struggle there, just as they do in the more diverse Northeast and West Coast.

So could the GOP return from Southern exile to its origins in the Midwest? Doing so would refute the geographic argument that it’s the party of the Confederacy. But that’s mainly because the Confederacy ain’t what it used to be.