Who voted Republican in the Solid South?

[ag]

Blacks (the few who could), (offspring of) carpetbaggers and scalawags and more recent transplants and other outcasts/contrarians, patronage employees of Republican administrations (with families), those who tried to play some role in Republican party politics nationwide (remember: they may have been hopeless outsiders in an election, but they still played a role in the RNC).

I mean, the numbers were tiny. Coolidge got

1,123 votes in SC
8,494 votes in MS
24,670 votes in LA
30,300 votes in GA
40,516 votes in AL
130,023 votes in TX

If in four of these they almost look like respectable percentages (over 20% in some cases) of votes cast, it is only because so few people, in fact, voted in the general election in any case. Census numbers for 1920 show the following populations

1,683,724 residents in SC
1,790,618 residents in MS
1,798,509 residents in LA
2,895,832 residents in GA
2,348,174 residents in AL
4,663,228 residents in TX

Even accounting for those not eligible to vote, these are ridiculous numbers (and ridiculous overall turnouts, BTW)

[ag]

Some of them were probably northern transplants.  Others might have been supporters of civil rights.

I can't comment that far back, but I know by at least the 1940s and 1950s, Southern Republicans were mostly in agreement with Southern Democrats on civil rights; their main campaign issues were arguing against one-party rule and moving the South in a more industrialized direction, IIRC.

You are right about most Southern White Republicans. Obviously, people like the MLK family (as black Atlanta elite, they, actually, voted, and, generally, voted Republican) did not share in that agreement

[ag]

German immigrants in the South were very Republican. Kendall/Gillespie Counties in TX were good examples of that.

Well, some of that goes to the Civil War.

https://en.wikipedia.org/wiki/Treue_der_Union_Monument