Arthur was a Republican.
OK Genius, now tell us what channel CNN was on back in 1866.
Arthur was elected Vice President in the election of 1880, becoming president upon the assassination of Pres. Garfield.
CNN wasn't around back then but the New York Times and the Washington Post were.
Actually I was just joking about the media thing, but the fact that Arthur hid some of the facts relating to whether he was a "natural born citizen" is an important part of history.
Donofrio's case was that the British citizenship conferred on Obama (and Arthur) by their fathers made them ineligible under the natural-born citizen clause. Some people differ on whether this is true and as Donofrio's case was thrown out, his point has not yet been tested in court.