Just curious.... are you aware that some of the Founding Fathers wanted to free their slaves, but there were laws prohibiting them from doing so?
What few people care to admit, is that once the Constitution was ratified, slavery was doomed to end; it was just a question of when it would end. You know... that pesky little phrase "all men are created equally "? The DOI really says that. Really. It does.
During the Revolutionary War, several slaves in Massachusetts sued in state courts for their freedom, citing the language in Jefferson's Declaration of Independence that all men are created equal and are endowed by their Creator with certain unalienable rights, including rights to life, liberty, and happiness (here, Jefferson clearly plagiarized John Locke). The Mass. courts agreed with these suits, and by 1783, many of the Northern states began mass manumissions of slaves. However, the vast majority of North American slaves existed in places like North & South Carolina, Virginia, Maryland, Delaware. So many slaves lived in these states and were so instrumental to those states' economies that the southern states doubled-down on slavery by the time of the 1787 Constitutional Convention.
A note on northern states' manumission plans: Many of them required gradual manumission, such as New York, which freed its last slave in 1843.
It's also important to note that as northern states' slaves were freed, they were not extended basic citizenship rights and oftentimes could not vote or hold property, and remained a vulnerable population in the Early Republic, as were Indians and Catholics and women.
http://slavenorth.com/emancipation.htm
See also Joseph Ellis's book
The Quartet. It's about what the founding generation believed they were doing by drafting the Constitution.
