The U.S. Open Pool Championship, formerly the U.S. Open Nine-ball Championship, is an annual professional men's nine-ball pool tournament that began in its current form in 1976. The U.S. Open is one of the most sought-after titles in nine-ball and in pool generally. Traditionally, winners of the U.S. Open are given a green blazer and are awarded free entry fees to all future U.S. Open tournaments.