>>64006290
If immigration hadn't increased in the 1820-1860 period (e.g., if the introduction of the locomotive to the USA and deployment of the B&O line had been delayed), the USA could've turned out similarly. Plantation owners would've eaten up the South, then the northern latitudes, while suppressing abolitionist politics with lobbying efforts. There was a general trend of plantation owners intentionally breeding them to get a larger supply of low caste labor. (4.5M by 1860, approx. 75% of Mexico's population, compared to 13M whites, half of whom immigrated during this period.)
Slower funding/development for the rail lines that enabled settlement of the West by the middle class German/Irish immigrants means more plantation soil.
Mexico or the UK could've broken this with just the threat of slave support.
South Africa is just an abandoned plotline using natives as a stand-in.