African Americans, in what is now usually called the 'Great Migration', made up of a sizeable portion of people on the move to cities in the 1920s. One and a half million black people moved from the South, doubling the black population of New York, Chicago, Detroit and Houston in this decade. In most cities however, racial discrimination blocked opportunity. Forced by low wages to seek the cheapest housing, black newcomers were forced into ghettos, like Chicago's South Side and New York's Harlem.