The Desire was the first American
slave ship. It was built in the town of
Marblehead, Massachusetts and completed in 1636. It was 120 tons and the third ship built in the Colonies. Its holds were divided into racks, 2 feet by 6, fitted with
leg irons and bars. Previously, only English ships carried slaves. With this, America fully participated in the slave trade not only as a consumer but as a trader.
On its maiden voyage on March 2, 1637, it exported captured Pequot Indian slaves to the West Indies. On its return, it brought back African slaves to Connecticut. Through the rest of its existence, it transported captured slaves from Africa to the West Indies, Virginia, and Georgia (a route called the Middle Passage).
Sources:
Purdin, Bill. Marblehead Magazine History Timeline. http://www.legendinc.com/Pages/MarbleheadNet/MM/Articles/Timeline.html
Zinn, Howard. A People's History of the United States: 1492 - Present. Twentieth Anniversary Edition, 1999. p. 29.