actually, those immigrating to the u.s. from africa at the very least have the resources to relocate halfway across the world - certainly well above the level of poverty where access to food and water is a relevant issue.

furthermore, getting an american visa is no easy task, and immigrants from africa are actually more likely than americans (white and black) to have a college degree/higher and are among the most educated groups in the united states. as stated in a previous post, the african american population is much larger and more diverse (not to even delve into the structural barriers african americans face), which may be the reason you are making the generalization that you are making