List of champions of the 1899 U.S. National Championships tennis tournament (now known as the US Open). The men’s tournament was held from 14 August to 21 August on the outdoor grass courts at the Newport Casino in Newport Rhode Island. The women’s tournament was held from 21 June to 24 June on the outdoor grass courts at the Philadelphia Cricket Club in Philadelphia PA. It was the 19th U.S. National Championships and the second Grand Slam tournament of the year.