in the 1770s, blacks throughout new england began sending petitions to northern legislatures demanding freedom. at the constitutional convention many slavery issues were debated and for a time slavery was a major obstacle to passage of the new constitution. as a compromise the institution of slavery was acknowledged although never mentioned directly in the constitution. an example is the fugitive slave clause. by 1789, five of the northern states had policies that started to gradually abolish slavery: pennsylvania (1780), new hampshire and massachusetts (1783), connecticut and rhode island (1784). vermont abolished slavery in 1777, while it was still independent. when it joined the united states as the 14th state in 1791, it was the first state to join that had no slavery. by 1804 all of the northern states had abolished slavery or had plans in place to gradually reduce it. there were 11 free states and 11 slave states. later came the civil war.