I, too, am America.
This final line is obviously a nod back to the the first line of the poem and emphasizes consistency in identity. The second half of the poem discusses the equality that Hughes hopes will be present in America in the future. That being said, the fact that Hughes repeats that he is America both before and after this ideal social shift shows that regardless of the Black condition in America, their importance to and presence in the country won’t change. As slaves, they are America. As equals, they are America.