He wrote that the North was too aggressive toward the South and should stop interfering in the slave states.

VOA: special.2009.05.14

The North and the South had roughly, as the Northern and Southern states, the Free states and Slave states, had roughly the same geographic size.

北方和南方大致上,北方和南方的各州有,自由州和蓄奴州的区别,但其地理大小总体上相同

耶鲁公开课 - 美国内战与重建课程节选

By 1860 there were approximately 4,000,000 slaves in the United States, the second largest slave society slave population--in the world.

截至1860年,美国大约有,四百万的奴隶,也因此使之成为了,世界历史上的第二大奴隶社会

耶鲁公开课 - 美国内战与重建课程节选

Four more slave states joined the Confederacy but four remained within the Union.

WHITEHOUSE: Abraham Lincoln

There was also no sign on Tuesday of an accord on another issue at the conference -- African demands that former slave states make a formal apology for some 400 years of human trafficking up to the early 19th century, during which some 12 million people where shipped in chains to the Americas.

CNN: New racism declaration unveiled

It came to the United States through the slave tales and narratives.

NPR: Encyclopedia Surveys World of Hip Hop