Yeah I did a bit more research. Looks like the cotton gin did greatly increase demand for slaves but that's not really related to steam engines. Combined with

Yeah I did a bit more research. Looks like the cotton gin did greatly increase demand for slaves but that's not really related to steam engines. Combined with the fact that one of the primary applications of the steam engine was faster transportation of goods in the North (South had little in the way of industrialization until post Civil War), I'm almost certain that the steam engine did not decrease the need for slaves. Once the North began expanding European trade routes post War of 1812 and the entire continent started demanding Southern US cotton, it was an avalanche (that did not get tempered by the ban on international slave trading).