TX, one of the most Republican states based on voting, is also among the least white.
That’s because the Texas electorate is a little more white than the overall population, and whites in Texas routinely vote 70+% for the GOP. That is why they dominate the state...for now. Eventually mass immigration will break the GOP hold on Texas, as the white share of the electorate falls below the point where winning 70% of them (plus the usual showing with non-whites) guarantees victory.
How long before that changes?
That's due to a combination of low voter turnout among Hispanics, combined with a very conservative white electorate with high voter turnout.