Despite many slaves being emancipated during and right after the american revolution, why did the number of slaves increase by 200,000 from 1776–1790?

During the Revolution the united colonies did not import new slaves as part of the embargo of English products. Following the revolution the international slave trade was continued by certain southern states and new slaves were brought in especially by South Carolina and Georgia. These slaves were vital to the agrarian economy of the south with its labor intensive farming.