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. U.S. Open 1975: June 19–23, 1975 at Medinah Country Club, Course No. 3. Champion: Lou Graham, at 287 (+3), playoff. Wiki link