The 1910 U.S. Open was the sixteenth U.S. Open, held June 17–20 at Philadelphia Cricket Club in Chestnut Hill, Pennsylvania, a neighborhood of northwest Philadelphia. Alex Smith, the champion four years earlier, prevailed in an 18-hole playoff over his younger brother Macdonald Smith and 18-year-old John McDermott to win his second U.S. Open. On Friday, Alex Smith opened with a pair of 73's to take the 36-hole lead by two shots ahead of McDermott, Gilbert Nicholls, Fred McLeod, and Tom Anderson. The course also hosted in 1907 and is the present-day St. Martin's course, now nine holes.