The 1912 U.S. Open was the 18th U.S. Open, held August 1–2 at the Country Club of Buffalo in Amherst, New York, a suburb east of Buffalo. (The course is now Grover Cleveland Golf Course, owned by Erie County. The Country Club of Buffalo relocated several miles east in 1926 to Williamsville (42.972°N 78.727°W / 42.972; -78.727).) Twenty-year-old John McDermott successfully defended his U.S. Open title, two strokes ahead of runner-up Tom McNamara.
At the end of the second round on Thursday, Mike Brady, Percy Barrett, and Alex Smith were tied for the lead, with defending champion John McDermott two back. In the third round on Friday morning, played in rainy conditions with thunderstorms threatening to disrupt play, McDermott managed to card a 74 despite hitting two drives out of bounds. He still trailed Brady by three going into the final round in the afternoon, but Brady struggled on his way to a 79 and 299 total. Tom McNamara, seven back at the start of the round, fired a course-record 69 to post 296 total. His 142 over the last two rounds was a new tournament record. It was still not enough to catch McDermott. Despite a bogey on the last hole, McDermott carded a 71 for a 294 total, 2-shots ahead of McNamara.
McDermott, age 20, was already a two-time U.S. Open champion, but by 1914 his golf career was over. After a series of personal setbacks, he began suffering from mental illness and spent most of the rest of his life in a mental institution.
Future U.S. Open champion Jim Barnes played in his first U.S. Open here, finishing in 18th place. Horace Rawlins, the winner of the inaugural Open in 1895, made his final appearance and missed the cut.
The par-6 10th hole measured 606 yards (554 m), the longest hole in U.S. Open history up to that point and the only time a hole was given a par more than five.