Portugal imported more African slaves than the United States and its predecessor colonies

See ‘African Europeans’ Review: Recalling Forgotten Pasts by Howard W. French.

"In 1472, two decades before Columbus sailed for the New World, so great was the demand for African labor in Portugal that the parliament urged King Afonso V to bar the sale of Africans to other European countries, especially to rival Spain, whose market for bound blacks was equally insatiable. By the mid-16th century, about 10% of Lisbon’s 100,000 inhabitants were Africans who had been brought to the city as slaves. At the time, 30,000 other blacks lived scattered throughout Portugal, whose overall population barely numbered one million people.

Portugal outlawed the importation of slaves in 1761, after its ships had delivered roughly 400,000 Africans in chains to the country. That is a larger number of slaves than the United States and its predecessor colonies imported from Africa during the entire history of slavery in America."