Some historians say he certainly won't be the first president with Black ancestors - just the first to acknowledge his Blackness.
Presidents Thomas Jefferson, Andrew Jackson, Abraham Lincoln, Warren Harding and Calvin Coolidge all had Black ancestors they kept in their genealogical closets.
Harding did not deny his African ancestry when Republican leaders called on him to deny his "Negro" history. He said, "How should I know whether or not one of my ancestors might have jumped the fence?"
Does African ancestry make these men Black? If the bar is the one-drop rule, then yes. The one-drop rule is a historical term used during the Jim Crow era that defines a person with one drop of sub-Saharan-African ancestry as not white and therefore must be Black. If that's the bar, then there have already been other Black presidents, says historian Leroy Vaughn, author of Black People and Their Place in World History.
The first president with African ancestry was Jefferson, described as the "son of a half-breed Indian squaw and a Virginia mulatto father." Jefferson also was said to have destroyed all documentation attached to his mother, even going to extremes to seize letters written by his mother to other people.
Vaughn cites an article written in The Virginia Magazine of History that states Andrew Jackson was the son of an Irish woman who married a Black man. The magazine also stated that Jackson's oldest brother had been sold as a slave.
Lincoln was said to have been the illegitimate son of an African man. Lincoln had very dark skin and coarse hair and his mother allegedly came from an Ethiopian tribe. His heritage fueled so much controversy that Lincoln was nicknamed "Abraham Africanus the First" by his opponents.
Warren Harding apparently never denied his ancestry. According to Vaughn, William Chancellor, a professor of economics and politics at Wooster College in Ohio, wrote a book on the Harding family genealogy. Evidently, Harding had Black ancestors between both sets of parents. Chancellor also said that Harding attended Iberia College, a school founded to educate fugitive slaves.
Coolidge supposedly was proud of his heritage. He claimed his mother was dark because of mixed Indian ancestry. Coolidge's mother's maiden name was "Moor," and in Europe, the name "Moor" was given to all Blacks, just as "Negro" was used in America. It later was concluded that Coolidge was part Black.