When, however, James Otis, Patrick Henry and Thomas Jefferson began to discuss the natural rights of the colonists, then said to be oppressed by Great Britain, some of the patriots of the Revolution carried their reasoning to its logical conclusion, contending that the Negro slaves should be freed on the same grounds, as their rights were also founded in the laws of nature.[1] And so it was soon done in most Northern commonwealths.
Vermont, New Hampshire, and Massachusetts exterminated the institution by constitutional provision and Rhode Island, Connecticut, New Jersey, New York and Pennsylvania by gradual emancipation acts.[2] And it was thought that the institution would soon thereafter pass away even in all southern commonwealths except South Carolina and Georgia, where it had seemingly become profitable.

There came later the industrial revolution following the invention of Watt's steam engine and mechanical appliances like Whitney's cotton gin, all which changed the economic aspect of the modern world, making slavery an institution offering means of exploitation to those engaged in the production of cotton.

This revolution rendered necessary a large supply of cheap labor for cotton culture, out of which the plantation system grew.

The Negro slaves, therefore, lost all hope of ever winning their freedom in South Carolina and Georgia; and in Maryland, Virginia, and North Carolina, where the sentiment in favor of abolition had been favorable, there was a decided reaction which soon blighted their hopes.[3] In the Northern commonwealths, however, the sentiment in behalf of universal freedom, though at times dormant, was ever apparent despite the attachment to the South of the trading classes of northern cities, which profited by the slave trade and their commerce with the slaveholding States.

The Northern States maintaining this liberal attitude developed, therefore, into an asylum for the Negroes who were oppressed in the South.
The Negroes, however, were not generally welcomed in the North.