UNIVERSITY PLACE, Wash. — Chambers Bay Golf Course had already served as the backdrop for one big event in the life of the 21-year-old Jordan Spieth. A month after Spieth won his first pro event as a PGA Tour rookie, he was a witness at a wedding on the grounds between his caddie, Michael Greller, and the former Ellie Morris.

Two years later, it was Spieth’s turn to have a monumental moment all his own. With a one-stroke victory over Dustin Johnson and Louis Oosthuizen on Sunday in the 115th United States Open, Spieth became the first male player since Gene Sarazen in 1922 to win multiple majors before his 22nd birthday. He also became the youngest winner of the national championship since Bobby Jones in 1923. Spieth, the reigning Masters champion, is the sixth man to win the first two legs of the Grand Slam, and the first since Tiger Woods in 2002.

Spieth, whose birthday is in July, opened with a bogey but closed with two birdies on his last three holes for a one-under 69 and a 72-hole total of five under. Playing in the group behind Spieth, Dustin Johnson three-putted from 12 feet for a par on 18 to finish with a 70. He was tied for second with Oosthuizen, the 2010 British Open champion from South Africa, who played the final nine holes in a record-equaling six-under 29 for a 67.