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

The southern states, virtually devoid of non-slave labour, relied on the people flocking to the mills of Lancashire to turn their fleecy raw material into finished cloth.

ECONOMIST: Cotton

Some of Congress's fiercest fights were over the admission of new states to the union, and whether they should be slave or free.

ECONOMIST: American democracy