History of slavery in the United States by state

On the whole, the former Thirteen Colonies abolished slavery relatively slowly, if at all, with several Northern states using gradual emancipation systems in which freedom would be granted after so many years of life or service.

(Vermont and New York had clear and absolute freedom dates; Massachusetts and New Hampshire were de facto free states with total abolition from the American Revolution forward.)

Fifteen states (in order of admission, Delaware, Georgia, Maryland, South Carolina, Virginia, North Carolina, Kentucky, Tennessee, Louisiana, Mississippi, Alabama, Missouri, Arkansas, Florida, and Texas) never sought to end slavery, and thus bondage and the slave trade continued in those places, and there was even a movement to reopen the transatlantic slave trade.

The prospective end of slavery would have thus deprived slave owners of the disproportionate representation of their interests in the national legislature, relative not just the people they enslaved but to free white male voters in other states.)

[1] The federal district, which is legally part of no state and under the sole jurisdiction of the U.S. Congress, permitted slavery until the American Civil War.