For about 300 years, European ships carried about 12 million Africans to America. This was one of the three pillars of the triangular trade, which enriched the colonial elites of the major European powers. Is it possible that this fact was properly represented in EU4? Certainly, this trade changed the demographics of much of America and West Africa.
Also, do not forget the slave trade conducted by barbary pirates. In this case, the slaves came from the Mediterranean and Atlantic coasts. From Cornwall to Greece.
I propose that there is some way to establish trading posts on the African coast, as actually happened. These trading posts would be responsible for supplying slaves to the American plantations and mines. And, in turn, these American plantations and mines, would benefit the colonial powers.

Also, do not forget the slave trade conducted by barbary pirates. In this case, the slaves came from the Mediterranean and Atlantic coasts. From Cornwall to Greece.
I propose that there is some way to establish trading posts on the African coast, as actually happened. These trading posts would be responsible for supplying slaves to the American plantations and mines. And, in turn, these American plantations and mines, would benefit the colonial powers.