The free black population of the South multiplied several times over between 1776 and 1800, but even in the Chesapeake Bay Region it was still very heavily outnumbered by the slave population. The city of Baltimore was the only place in the region where there were more free blacks than slaves. With hindsight, it is possible to see the beginning of the process which would eventually make Maryland as much a state with free black as a slave state, but as Richard Dunn has observed, the experience of Virginia was very different. There, during the early. Of the United States, slavery was still expanding and strengthening its grip.
Paradoxically, the new expansion to place within limits which were themselves been defined with increasing sharpness. It is true that the wave of post-test Revolution manumissions soon subside, and legal and social pressures discouraged further resort to them.  but, if constraints within the South weekend, restrictions imposed from outside gained strength during the following decades. In the North, where slavery had more much shallower Roots, the awkward question raised by the ideology of the Revolution found a more receptive audience. During or after the revolution, the northern states all committed themselves to the abolition of slavery, although the process was painfully slow in some cases.
The Northwest Ordinance of 1787 kept slavery out of the vast territory to the north of the Ohio River, although for more than 30 years attempts were made to break down the barrier. The stage was set for the parallel and completitive expansion of freedom and slavery into the Great Central Valley of the United States. In 1820, the Missouri Compromise Barb slavery from most of the huge Louisiana Purchase and, in fact, left slavery with little further scope for expansion in the remaining territories of the United States as they then existed. It’s about the ability of Supply to keep Pace with demand for slave labor were raised by the ban on the importation of slaves imposed in 1808. The Constitution had prevented any such ban before 1808, but Congress lost no time in acting once it had the Constitutional authority to do so.Mass movement of slaves into the deep south and the Southwest sowed the seeds of slavery’s relative decline in the upper South. By the 1830s the rising Abolitionist Movement in the north added moral strictures to the territorial restrictions of slavery.
External moves to circumcise slavery, actually was given a new lease on life during the same period. It’s Westward surge shifted the whole center of gravity of the South’s peculiar institution dramatically from the upper South to the Deep South and from east to west. The key to that expansion lay in Cotton. In the agree culture of the colonial South, cotton was a very minor crop indeed semi color in the generation after 1790, it came into power in the southern Kingdom. Demand, technology, land, and labor came  together to launch the cotton boom. The demand came from across the Atlantic, above all from Britain, what did The Logical Innovation put cotton Mills in the Forefront of the Industrial Revolution. Southern ability to meet the demand dependent on another, and simply are, technological development – the cotton gin. With the removal of the Native Americans from large areas, South Carolina and Georgia became the first major Cotton States; but, particularly after the war of 1812, settlement poured onto the rich soil of the black belt in Alabama and Mississippi, which became the heartland of the cotton Kingdom. Slave labor supplied the other necessity of the expanding Realm.