The BBC has an article, Americans seek their African roots, on DNA testing of black Americans. The article states that "Of the half a million Americans who have purchased DNA tests, around 35,000 of them are African American."
The article reports criticism of African Ancestry, the only black-owned DNA testing firm and the first to cater specifically to African Americans. Professor Deborah Bolnick of the University of Texas is quoted as being particularly critical of African Ancestry reacting to the company claim of being "the only company whose tests will place your African ancestry in a present day country or region in Africa" with the comment "It's really much more uncertain than the testing companies make out."
In my view its unfortunate that North American media have gone overboard in taking the results of these tests, which should be expressed in probabilistic terms, and running with the most likely indicated origin to make it seem certainty. That goes for most if not all such regional origin type conclusions, not just for blacks.