I’ve mentioned this before here.
I will share this again though because these climatic and environmental differences within the United States decisively shaped the Old South.
The following excerpt comes from William A. Link’s book Southern Crucible: The Making of an American Region:
“From 100,000 BC to about 10,000 BC, much of the Northern Hemisphere was submerged in ice and glaciers, but glaciation stopped at approximately the Mason-Dixon line. That the South was nonglacial made its soil and geography distinctive from that of the North, and helped create a distinctive ecosystem with common environmental and geographic characteristics. A warm climate encouraged the development of staple-crop agriculture; tobacco, cotton, rice, and sugar were well adapted, while grasses and small grains did not survive well. Typically, southern soil is either heavy clay or sand, characteristics resulting from the varying impact of the last ice age.”
There is still this dumb idea that floats around even to this day that slavery alone made the South distinct from the North, not the underlying differences in climate and geography that made the South more hospitable to slavery and cash crop agriculture.
The differences between the North and South pile up when you start studying the physiography and environmental history of the respective regions. The fact that much of the North was covered by glaciers for thousands of years is one of the biggest differences. There are huge differences in animal and plant life because the South is more biologically diverse.