Although the above arguments may seem compelling, it seems they can t be right. Slave labor cannot compete with free labor, but this does not mean the former cannot survive if it is propped up by government. Because certain individuals profit from them. In the same way, certain individuals had a vested interest in the maintenance of slavery. The most obvious example is the class of slaveholders.
Slavery is an unjust system.
But it is also an inefficient one. It was no coincidence that the North blockaded and invaded the South, and not vice versa. A society based on slave labor will never be as industrious as one based on free labor. Modern blacks are certainly poorer because of slavery. But so are modern whites.