JFK changed the landscape, and also, history was taught differently: they almost never mentioned that Southern leaders who were against the civil rights act were mostly—if not all—Dims.
If you are old enough, you don't have to look it up. You rely on your (perhaps faulty) memory.
As I remember it, Negroes (the polite term at the time) voted predominantly republican until Lyndon Johnson got credit (with enough republican votes to make up for southern democrats) for passing the Civil Rights Act. Al Gore Sr, Democrat of Tennessee, was among the senators voting against.
Since then, the civil rights race-baiters have aligned with democrats. The overwhelming majority of African-Americans went along with them.