During the Revolution, all of the new states banned or suspended the international slave trade. Most slaves arrived on English ships, and even those on American ships were purchased from agents of the Royal African Company stationed on the west coast of Africa. Thus, all the colonies (which soon became the states) banned the African slave trade as part of their overall policy of refusing to import anything from Britain. The "non-important" movement was an attempt to cut all economic ties with Britain. Since most slaves were brought in by British ships, and virtually all were purchased from the British on the coast of Africa, a ban on the trade was an important part of the colonists' general policy not to trade with Britain.
In March 1794, Congress prohibited the use of any U.S. port or shipyard for the purpose of fitting out or building any ship to be used for the introduction of slaves. The law also prohibited ships sailing from U.S. ports from trafficking in foreign countries. Ships sailing from the United States to Africa, even if of foreign registry, were required to "give bond with sufficient sureties, to the treasurer of the United States, that none of the natives of Africa, or any other foreign country or place, shall be taken on board... to be transported, or sold as slaves in any other foreign place, within nine months thereafter." Penalties under the law included fines ranging from $2,000 for outfitting a ship to $200 for an individual working on such a vessel. The act provided that the ships could be confiscated, and half of all fines given to any informants, thus providing an incentive for ship captains and mariners to monitor the activities of anyone they suspected of being involved in the illegal slave trade.
Until 1800 none of the states had reopened the African trade, which had been effectively closed since the Revolution. Before 1800 all introductions into the U.S. were thus illegal, even if the slaves were brought in by foreign ships. After 1800, however,
Georgia and South Carolina reopened their international slave trade, and in the next eight years, these two states would introduce about 100,000 new slaves from Africa.