On the first hole at Congressional Country Club, as each golfer tees off, 24 marshals watch the ball -- and the crowd. They're volunteers from Argyle Country Club in Silver Spring, each working a six-hour shift, but some put in days as long as 14 hours.
"It's kind of nice having the honor of being on the first hole," said volunteer Beale Cummings. "Argyle has been here longer than any other club, so we keep moving up."
They take pride in their work. "It's a little-known fact that the PGA raises more money for charity than the NFL and Major League Baseball combined," said Ronald Giles.
On the ninth green, volunteers from Lakewood Country Club in Rockville keep a watchful eye on the action, but that's not to say they're not having fun.
"Primarily the reason we all do this is just a reason to watch professional players and their habits and how they approach the game," said Mike Simon. "It's just really enjoyable for us."
Meanwhile, keeping the crowds moving, without disturbing the players, is a job for another group of volunteers.
No matter what area they focus on, each volunteer must buy their own uniform, which costs $160. Some people travel from across the country, incurring all kinds of expenses and using vacation time just to help out at the U.S. Open.
Ken Westgate and his wife Sue came from Grand Rapids, Mich., to volunteer in the merchandise tent helping the vendors, while Doug Coulson handles the stands at the first tee. "I come every year," Coulson said. "I spend a week, and this is fun. I just do it to volunteer."