<span>Instead, in 1857, in the case of Dred Scott v. Sanford, the United States Supreme Court declared that all blacks — regardless of whether they were slaves or free men — were not and could never become citizens of the United States. The court also ruled that the 1820 Missouri Compromise was unconstitutional.</span><span>Dec 13, 2010</span>
I believe it was because of things like segregation and "separate but equal." Even after obtaining citizenship they were still discriminated against by most.
