The Great Civil Rights Switch of the 1960s:
How many times have you heard "But the parties switched in the 60s! (you racist)"? I hear it all the time, including the "racist" bit as some angry leftist incorrectly assumes I'm a republican for having disagreed with one of their "pro"gressive SJW narratives.
We all know that the bulk of republicans and southerners today aren't what the left claims, but it's difficult to argue the fallacy of "the big switch" without data.
This video does a great job of pointing out key events and timing which bust the myth of the great civil rights switch of the 60s.