"The essence of United States slavery was forced labor. Enslaved people's unrequited toil built a significant portion of the nation's wealth. They labored in many farming, mining, construction, transport, and factory settings. But by the 1830s most worked in cotton fields in the Deep South in the most important sector of the American economy. The cotton bales they made streamed into factories in New and old England, spun into yarn and woven into fabric clothing people across the globe. Cotton shipped abroad each year increased from just a few thousand bales in 1790 to four million by 1860."--Provided by publisher.