The slave trade became illegal when the United States enacted a law banning the importation of slaves

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The United States officially banned the importation of slaves on January 1st, 1808. The slave trade had an important place in American history. Here, slaves were shipped from Africa to the United States during the period when the slave trade was legal. Several hundred thousand slaves were brought into this country during the colonial period in the early 19th century.

In 1808, the ban basically stopped the importation of slaves from Africa or the West Indies. However, slavery continued in the country. Also, there was some smuggling of slaves. Here, the ban was not totally enforced. It did not abolish slavery immediately. But it certainly ended the legal, open, and fair situation of the importation of slaves. 

Most likely we can say, this ban was the first international human rights movement. Also, it united black people and white people. It really helped to increase human rights in this world.