WWII and FDR's support for Allies against Wilkie's more isolationism resulted in a WASP Yankee swing to FDR.
Undoubtedly correct. FDR’s support for the Allies had the same effect in parts of
Appalachia. In Unionist northwestern North Carolina, FDR is the only Democrat to win a majority in Davie County since 1900, and he did better than any Democrat in Wilkes County (ironic given the name of his opponent?) since Winfield Hancock reached 48 percent in 1880, and better than any Democrat ever in Yadkin County. In arch-Republican Avery County, Willkie lost seven percent on Alf Landon. In East Tennessee, FDR won Roane County, which had previously never voted for a Democrat since the Civil War, and was the first to win a majority in nearby McMinn County since then.
People probably overlook that Obama’s two elections, and to some extent the 2000 election, are exceptions to the tendency of Yankee and Appalachian counties to move in tandem with each other. Common enemies – planters historically, now Latinos and immigrant welfare – have linked these two regions ever since the Civil War and even beforehand.