permitted this prohibition: January 1, 1808. During the Revolution and in the following years, all states north of Maryland took steps towards abolishing slavery. In 1777, the Vermont Republic, which was still unrecognized by the United States, passed a state constitution prohibiting slavery. The Pennsylvania Abolition Society, led in part by Benjamin Franklin, was founded in 1775, and Pennsylvania began gradual abolition in 1780. In 1783, the Supreme Judicial Court of Massachusetts ruled in Commonwealth v. Jennison that slavery was unconstitutional under the state's new 1780 constitution. New Hampshire began gradual emancipation in 1783, while Connecticut and Rhode Island followed suit in 1784. The New York Manumission Society, which was led by John Jay, Alexander Hamilton and Aaron Burr, was founded in 1785. New York state began gradual emancipation in 1799, and New Jersey did the same in 1804. Shortly after the Revolution, the Northwest Territory was established, by Manasseh Cutler and Rufus Putnam (who had been George Washington's chief engineer). Both Cutler and Putnam came from Puritan New England. The Puritans strongly believed that slavery was morally wrong. Their influence on the issue of slavery was long-lasting, and this was provided significantly greater impetus by the Revolution. The Northwest Territory (which became Ohio, Michigan, Indiana, Illinois, Wisconsin and part of Minnesota) doubled the size of the United States, and it was established at the insistence of Cutler and Putnam as "free soil"no slavery. This was to prove crucial a few decades later. Had those states been slave states, and their electoral votes gone to Abraham Lincoln's main opponent, Lincoln would not have become President. The Civil War would not have been fought. Even if it eventually had been, the North might well have lost. Constitution of the United States Slavery was a contentious issue in the writing and approval of the Constitution of the United States. The words "slave" and "slavery" did not appear in the Constitution as originally adopted, although several provisions clearly referred to slaves and slavery. Until the adoption of the 13th Amendment in 1865, the Constitution did not prohibit slavery. Section 9 of Article I forbade the Federal government from preventing the importation of slaves, described as "such Persons as any of the States now existing shall think proper to admit", for twenty years after the Constitution's ratification (until January 1, 1808). The Act Prohibiting Importation of Slaves of 1807, adopted by Congress and signed