I'm not a history professor but I think in the mid 1960's Lyndon B. Johnson signed the civil rights act and kicked the racists out of the Democratic party. I can't for the life of me remember which party they ran to and which party embraced them with open arms. Anyone?
A greater percentage of Republicans than Democrats in congress voted for the Civil Rights Act. Same for the Voting Rights Act the following year.
In 1968, George Wallace, a racist Democrat running as an Independent, got 45 electoral college votes - nearly 14% of the popular vote. Then Wallace saw the light, repudiated his racist beliefs, and became, er, remained a Democrat.
Who won the south in 1976? Jimmy Carter, a Southern Democrat.
No, you're not a history professor - and neither am I - but you don't know jack.