Who would a single-issue pro-rights-for-blacks voter vote for in each election?

[DabbingSanta]

a swing voter from 1904 until the Civil Rights Act

Why 1904?

I don’t know, I really just chose a date around when the two parties were jumbled up in terms of social issues. It could be 1896 or 1912 or whatever, just around the turn of the century.

I’m pretty sure Republicans were consistently better for civil rights until 1928.

I believe the first Democrat to win a large majority of African American votes was Roosevelt in 1936.  Key group in the New Deal coalition which lasted for generations.

I should add Republicans remained competitive in some senate/gubernatorial elections with black voters into the 1960s and early 70s, especially in the South.