Before the American Revolution, both the colonies and Great Britain regulated the African slave trade to what became the United States. The British government gave special protection to the Royal African Company, which brought more Africans slaves to the American colonies than any other single entity. The slave trade was an important part of Britain's mercantile policy: it collected taxes on the slaves while colonial governments both taxed them and occasionally sought to limit their arrivals.
After the Stono Rebellion (1739), South Carolina suspended the trade for a few years because its leaders believed that large numbers of freshly imported Africans would undermine the safety of the colony. Then in 1751 South Carolina imposed a special tax on foreign slaves to slow the trade and, nine years later, once again banned it altogether because leaders of the colony still feared the growing number of African-born slaves. The royal authorities disallowed the law. But in 1764 the colony levied new taxes on African-born slaves because, as the legislature noted, their rising number "may prove of the most dangerous consequence."
Shortly before the Revolution, Virginia also tried to ban the trade, not for prudential reasons but to prevent the outflow of capital from the colony. Virginians attempted to use prohibitive taxes to discourage the trade, but the Crown overruled this law, because the slave trade was vital to the British economy and because the Royal African Company had powerful patrons in the government.