✒ Answer
Slavery was so profitable, it sprouted more millionaires per capita in the Mississippi River valley than anywhere in the nation. With cash crops of tobacco, cotton and sugar cane, America's southern states became the economic engine of the burgeoning nation
Slaves provided agricultural and industrial labor, constructed fortifications, repaired railroads, and freed up white men to serve as soldiers. Tens of thousands of slaves were used to build and repair fortifications and railroads, as haule , teamsters, ditch diggers, and assisting medical workers.