What caused the expansion of slavery in the early 19th century? We often think of slaves working only as field laborers, but they were engaged in many different aspects of the American economy. What different roles did slaves play in the American econom

What caused the expansion of slavery in the early 19th century?  We often think of slaves working only as field laborers, but they were engaged in many different aspects of the American economy.  What different roles did slaves play in the American economy in the early 19th century?  How did regional differences affect slave living and work roles?  Provide specific examples/evidence to support your arguments.