President Lyndon Johnson's aid said that his pushing of the 1964 Civil Rights Act will cost the Democrats the South for at least a century. Much of the 60's South were single issue voters (segregation), and flocked to the Goldwater banner. After the Democrats abandoned the white supremacist vote, George Wallace had a good chance of forming a 3rd Party in the South (Republicans were still the hated Party of Lincoln).
The GOP, namely Nixon, saw that the South was up for grabs, and they courted the white supremacist vote. They let these crazy extremists into the GOP, and that's how they ended up with people like Rush Limbaugh and the Birthers.