And long before. Slavery has existed in several forms throughout Africa for many centuries, even up to today.

It primarily ramped up with the West Indies and England's Sugar Empire though. Between 1660 and 1700 around 260,000 slaves had been shipped to the West Indies to work sugar plantations. Only around 115,000 made the trip alive though. Harsh conditions on route.

Before then America primarily had an indentured servitude system with a relatively low number of slaves. The 'success' (yes, I say that recognizing it's from a certain point of view) of the West Indies is what set the stage for slaves to be brought into America on a much larger scale.

From my American history notes:

In Virginia:

1650 – 300 slaves (2%)

1680 - 3000 slaves

1700 – 13,000

1720 – 27,000

1750 - 150,000 slaves (18%)

In Maryland:

1680 - indentured servants outnumber slaves 4:1

1710 - slaves to servants 5:1

And then it's also interesting to note the transition of laws regarding slaves. When the first arrived, they weren't considered slaves. They were still brought in like other indentured servants from England.

Virginia slave codes

1619 first African slaves arrive, treated as indentured servants

1640 although not a law in England, first case of ‘servitude for natural life’ in VA

1662 Hereditary law enacted: “all children borne in this country shall be held bond or free only according to the condition of the mother”

1682 if slaves were not Christians in their native country they (+ their children) were slaves even if converted

1700 comprehensive code that divided society into black (un-free) and white (free)