The United States moved very slowly.

Individual States under the old confederation prohibited slavery within their borders, and in some cases the slave trade; but when our forefathers came together to form that Constitution under which the nation still exists, the opposition of certain Southern States was so vigorous that the best which could be done was to authorize a tax on slaves of not more than ten dollars a head, and to provide that the traffic should not be prohibited before 1808.

But there followed a series of acts which corrected the seeming failure of the constitutional convention.

One prohibited American citizens "carrying on the slave trade from the United States to any foreign place or country." Another forbade the introduction of slaves into the Mississippi Territory.
Others made it unlawful to carry slaves to States which prohibited the traffic, or to fit out ships for the foreign slave trade, or to serve on a slaver.

The discussion caused by all these measures did much to build up a healthy public sentiment, and when 1808--the date set by the Constitution--came round, a prohibitory law was passed, and the President was authorized to use the armed vessels of the United States to give it force and effect.