Why do people say Obama is the first black President?

No because do you remember that ruling of plessy v ferguson and other court cases? They basically said any drop of black blood makes you black. Perhaps you see Obama on the street ( pretend he's not president) you would think he's a black man . Saying the 44 white president is actually very ignorant for you to say and you sound uneducated I hope you are young so you don't make too much of a fool of yourself .