Summerhays closed with a 2-under 69 Sunday to win the Children's Hospital Invitational, doing what past amateurs like Sergio Garcia and Charles Howell III were never able to do in their stints on the developmental tour.
He finished at 6-under 278 to beat Chad Collins and Chris Nallen by two shots.
But a place in the history books is all he won: As an amateur, Summerhays wasn't eligible to collect the $126,000 first-place check. It didn't dampen his spirits afterward.
'It's been a really special week,' said Summerhays. 'I'll never forget that feeling and that atmosphere. There is nothing like that feeling -- of having people whistle and clap and cheer for you. It makes your heart want to break out of your chest. It feels so good.'
Nallen and Collins both took home $100,800 for second place, benefiting from Summerhays' amateur status.
Nallen, who shared the overnight lead with Summerhays, shot an even-par 71 to join Collins (69) at 4-under 280. Tjaart van der Walt had a 69 and finished alone in fourth place at 3-under 281.
The lead changed hands several times Sunday between Summerhays and Nallen and Collins, but Summerhays was able to pull out the win with a bogey-free 33 on the back nine.
He made his last two birdies at the 10th and 12th holes after closing the front nine at Ohio State's Scarlet Course with back-to-back bogeys.
Nallen and Collins both stumbled to late bogeys: Collins at the par-4 18th, and Nallen at the 15th and 17th holes, making it easier for Summerhays to win by cruising home with six straight pars.
'I played such a good back nine,' said Summerhays. 'I feel so blessed, so grateful, just to have had the opportunity -- and then to just have been able to stay calm out there and hit really good, aggressive, confident shots.
'I'm still trying to get used to the feeling.'