Barbarian observes:
In fact, there were democrats and republicans on both sides of the civil rights movement. On one side, opposing protection for minority voters, were conservatives. On the other side, advocating civil rights laws, were liberals.
It's still that way.
Racists fled the democrat party, and liberals and minorities fled the republican party. Just that simple.
See above. Kevin Phillips,one of the architects of Nixon's "Southern Strategy" clearly explained how it worked.
If you doubt this, list the liberals in Congress who voted against the Civil Rights Act,and the conservatives who voted for it. You won't like the results.