There's been a consistent faction within this country that has been aligned with white supremacist goals: southern, rural, conservative, states-rights whites. The name of that faction has changed over time. They were once the anti-Federalists. Then the Democratic Republicans. Then the Democrats. Then the Republicans. But regardless of what label they had at a given moment, you'd find the same basic collection of states, localities, and demographic groups in that faction. For example, compare the 1900 and 2000 election maps, and you'll see they're pretty close to identical, just with the colors flipped. The grandkids and great-grandkids of the racist Democrats of the early 20th century are the racist Republicans of the early 21st century.