Iirc, most of the immigrants of the 1800s came from northern Europe. Most will be happier with a similar climate.
The growth of the South East didn't really take hold until air conditioning was popularized in the 1950s.
Racism is endemic throughout North America (especially if you consider indigenous/native, or Irish a race).
Slavery enabled larger farms in the inhospitable climate of the southeast and caribbean, but the existence of slavery there did not magically suppress immigration, the climate and subsequent economy did.
Where do you think racism isn't endemic?
1) Ease of access. The North was geographically closer to Europe. In days when travel was slow, the difference was not trivial as it is now.
2) Climate. The median European latitude is roughly on par with Maine. The North would have felt more like home, while the South would have been very different (and not in a good way, in those days before AC!)
3) Northern Industrialization. The vast majority of the population (71%) and industry (~90%) was in the North. If you were looking for a job as an unskilled laborer, there was far more work up North.
4) Immigrant communities. In a sort of feedback loop, more immigrants in the North would naturally make it a more desirable destination for future immigrants. If you're a poor German immigrant who doesn't speak English, you'd feel more at home in a German neighborhood in New York City than in a Southern city which might not host a significant German community.
5) Slavery. Slavery undermined the market for free labor in numerous ways. First, most menial work was done by slaves. Second, slaveholders would 'lease' out their slaves to serve as laborers, with the pay going to the slaveholder. As a result, the going rate for labor was much lower in the South than in the North. Even if an immigrant aspired to farm their own land in the South, they would still be in competition with slave labor. In a sort of unvirtuous cycle, the existence of slavery meant that the only way to gain wealth in the South was to own slaves, which would have been cost-prohibitive for an immigrant.
The North arguably was more racist towards those Irish immigrants at the time, because the North was dominated by English Protestants (WASPs) while the South had roots in being from the poorer parts of the British Isles, which is the origin of the Southern accent.
I have never found this to be true in my travels. Just because you see it on TV doesn’t mean that’s how it works in real life.
I can understand the areas that border the Pacific Ocean, but what was up with the high immigration to desert states like Nevada, Arizona, Utah, etc.? Who would want to immigrate from (presumably) the green British Isles to the desert? Western Oregon and Washington would be more their climate.
The high migration/immigration rates in Nevada, Arizona, and Utah in the late 1800s is relative. There was such a small amount of people that it was easy to have a large percentage from out of the US.
Who was immigrating there? Well one group was the Mormons. Apparently the Mormons were successful early on recruiting in Britain and those people migrated to the US and directly to Utah. Later that flowed over into Nevada and Arizona.
Also early on in these western territories, many people were probably going there to mine which may have attracted overseas people directly, not so concerned with green fertile land.
Final thought. The people immigrating from Britain and Ireland were looking for land. They probably had little idea what the southwest US was like except they had been told that there was lots of land available. When they got there it was totally different but there was land and water. Also many may have been going to California but stopped on the way for various reasons.
Edit: also those states are known for their population in deserts but they do have a lot of non deserts: forest,grassland, etc. And many early settlers stopped in those areas before geographic forces started the big desert settlements.
But even setting aside the massive European colonial machinery, the average stay-at-home 18th or 19th century European already had plenty of ideas about what people of non-European races were like, from the stories of colonial wars, tales of explorers' encounters with savagery, and general mythology and exoticism of what the rest of the world must be like. And those opinions were not, let's say, generally very enlightened.
You can still be a racist even if you've never met someone of another race. If anything it's much easier that way.
Yes, very small fraction of Europeans was involved in that. Overwhelming majority never left their country, and often their village.