Hammer qualified for the Chambers Bay event after finishing second in a 36-hole U.S. Open sectional qualifier at Northwood Club in Dallas, having shot rounds of 64 and 68.
At 15 years, 10 months and 20 days, the Houston native will become the fourth-youngest player to take part in the U.S. Open, after making four birdies in his last five holes in a late bid for glory.
“This means the world to me,” Hammer told The Dallas Morning News. “I’ve dreamed about it my whole life. It’s going to be awesome.”
He added: “I was confident. I’ve been hitting it well and putting well, so I thought if I continue doing that here I’ll have a chance.”