Moore, 19, a sophomore at UNLV from Puyallup, Washington, grabbed the lead for good on the second hole of the scheduled 36-hole championship match. He strung together 10 birdies in the first 18 holes, including the last four in a row, to take a 6-up lead at the turn.
Moore was 9-up after 24 holes and closed out Williamson on the 27th hole. Moore finished with 14 birdies on the day, and his 18-hole score was equivalent to 63, breaking the course record of 65 he set in the quarterfinal round.
With the victory, Moore earned an invitation to the 2003 Masters, should he remain an amateur. The finalists received automatic berths into next month's U.S. Amateur at Oakland Hills.
'I've played in quite a few USGA championships,' said Moore, who missed the cut in last month's U.S. Open at Bethpage and was runner-up at the 2000 U.S. Junior Amateur. 'It feels good to finally win one.'
The margin of victory was the second-largest in tournament history. Jim Sorenson posted the biggest with a 12 and 11 triumph over Jay Cooper in 1985.
'When he birdied 15, 16, 17, and 18, I didn't even come close to matching that,' said Williamson, 23, of Crawfordsville, Indiana. 'That's pretty tough to come back from.'
The U.S. Amateur Public Links is one of 13 national championships conducted annually by the United States Golf Association, 10 of which are strictly for amateurs.