To those who say that slavery would have been abolished earlier: do you really think that the plantation owners and other slaveowners would have been any more willing to give up that practice under British rule than they were under US federal governance?

Remember that people owned slaves even in the northern colonies and that that practice continued into the early 1800s in the northern states. Heck, the Revolutionary War would never have gotten off the ground if the northern colonies' representatives at the Continental Congresses hadn't capitulated to pressure from the southern colonies to allow the practice of slaveholding to continue in the new republic. The law of the land in the entire United States, even though abolitionists in the northern states found it reprehensible, was that any escaped slave was to be returned to his or her owner no matter where he or she was found. And when the Civil War was finally waged, the majority of Union soldiers were more concerned with preserving the Union than with emancipation.

Given the apathy in the general population of the North and the high feeling on the subject in the South, I suspect that if Britain still ruled the American colonies in the 1830s when various legislation abolished slavery in the British colonies, the Revolutionary War would have been fought then and, if the American colonies had won as they well might have (given the resources of the North especially in light of growing industrialism), the United States might have been a slaveholding nation for even longer than it was.