The 1975 U.S. Open was the 75th U.S. Open, held June 19–23, at Medinah Country Club in Medinah, Illinois, a suburb northwest of Chicago. Lou Graham defeated John Mahaffey by two strokes in an 18-hole Monday playoff to win his only major championship. Arnold Palmer finished in a tie for ninth place, his final top-10 finish at the U.S. Open. Jerry Pate tied for 18th place and shared low amateur honors with Jay Haas; Pate won the following year as a tour rookie.