Then from 1820 to 1860, the forty years before the war, an estimated roughly two million American slaves were sold to satisfy the need of slave labor in the great cotton kingdom of the growing Southwest.

之后从1820年到1860年,这战争前的四十年间,据粗略统计有大约两百万美国奴隶被出售,以满足西南部,这个日益增长的棉业帝国对奴隶劳工的需求

耶鲁公开课 - 美国内战与重建课程节选