Soil was being eroded and wasted along the Eastern seaboard, and they were using up the great soils of the Mississippi Valley and over time that slave system just somehow wasn't going to work out.

东部沿海地区的土地因被侵蚀而荒废掉,密西西比河谷地区的土地资源即将被耗尽,但就在这种情况下,奴隶制依然能维持南方的经济

耶鲁公开课 - 美国内战与重建课程节选

And you will find, as we will in the next few weeks, the Southern political power by the 1850s and 1860s is really no longer in Virginia, or even South Carolina, it's out in the Mississippi Valley.

在接下来的几周课中你们会发现,截至十九世纪五六十年代,弗吉尼亚,南卡罗来纳州和密西西比河谷,已经不存在南方政权力量了

耶鲁公开课 - 美国内战与重建课程节选