African immigrants were brought to America by

The Great Migration, sometimes known as the Great Northward Migration or the Black Migration, was the movement of 6 million African Americans out of the rural Southern United States to the urban Northeast, Midwest, and West that occurred between 1916 and 1970.

African immigrants were brought to America by European slave traders from Portugal, Spain, France, the Netherlands and Great Britain.

Explanation:

African people were brought to America in European ships which belonged to different slave traders from the previous mentioned countries, in the context of the Trans-Atlantic Slave Trade, which consisted of three different strategic locations for exchange and commercialization before sailing to America: Europe, the Caribbean and West Africa.