Virginia's Shenandoah Valley has a huge number of Pennsylvania Dutch. German Moravian settlers immigrated heavily into North Carolina.
Let's not forget the Acadians in Louisiana and the Mexicans in south (like Laredo), central Texas (like San Antonio), and west (El Paso). OK, El Paso is in no way Southern -- and Texas is losing much of its old Southern character as has Virginia.
East Texas has always been deep southern, the area right next to slave holding LA. In 1992, Bill Clinton dominated in East Texas. Democrats today get absolutely wiped out there now sadly.