For all of its high principle, there is a dark side to this statement. In the century of the country’s founding, British colonies in the New World imported 1.5 million enslaved Africans. That is more than three times the number of European immigrants who sailed westward searching for some version of Jefferson’s vision. By the middle of the 19th century, the four million people of African descent in the U.S. made it the largest slave society in the world.