The main reasons were likely: 1) Ease of access. The North was geographically closer to Europe. In days when travel was slow, the difference was not trivial as

The main reasons were likely: 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.