Obama is the first Black American to be elected President of the United States of America. If you lived before the civil rights movement & saw how black people were treated you would understand what a milestone it is.
Actually, as far as I am concerned, he is half black & half white. His father was black, his mother was white. In the United States, if you have even a smidgen of black blood in you, then you are considered black. I have really never understood that, but that is the way it is.