Why was the slave trade abolished in 1807?

The United States Congress passed a law abolishing the slave trade in 1807 because that was the earliest that they were allowed to do so under the Constitution. When that document was written, many of the Framers, most from the North but also from Virginia, had wanted to abolish the trade, which even many slaveholders had come to see as immoral and cruel. Additionally, Virginia and Maryland planters had a surplus of labor, and if the external slave trade was closed, they could (and did) profit from an internal trade that saw their slaves shipped southward. But South Carolina and Georgia's delegates were bitterly opposed to such a measure, and the Framers, as part of a compromise that banned export taxes (while allowing import taxes) also protected the trade in human beings until 1808. Congress passed the law in 1807, but it was worded so as not to go into effect until 1808, and indeed another law . The British Parliament, under similar pressures, banned the trade more or less outright in 1807. We should note, of course, that the ban on the slave trade did not constitute a blow for the institution of slavery itself. It grew exponentially in the decades following 1807-08.