Think about it. While Latin America surely imported more slaves, they still also benefitted from immigration of poor whites from Europe as well. Currently the black population of many South American countries hovers around 30% (Brazil, Columbia, venezuela, etc)
Meanwhile in The US the black population has hovered around 12-13% for damn near the past 50 years. But in the late 1800's, many southern cities had overwhelmingly large black populations. Wonder what happened to all the black people?
White supremacy.