Thompson, 53, tied Carolyn Cudone's tournament record with her fourth consecutive title and became one of only four golfers -- male or female -- to win as many as seven USGA events.
En route to her latest triumph, Thompson tied, broke and extended the USGA mark for consecutive matches won in a single championship, finishing the tournament with her 24th straight.
"She doesn't make many mistakes," the 58-year-old Berkmeyer said.
Only Bobby Jones (9), JoAnne Gunderson Carner (8) and Anne Quast Sander (7) have as many USGA victories as Thompson, who won the U.S. Women's Amateur in 1973 and the U.S. Women's Mid-Amateur in 1990 and 1997.
Thompson also became the first qualifying medalist to go wire-to-wire since the format changed to match play in 1997. But that did not make her most recent victory any more special than the previous three.
"They're all special in their own way," she said. "The first one was special because I was expected to win. It got the monkey off my back."
For the fourth year in a row, the Women's Amateur trophy will be on display at Alleghany Country Club, Thompson's home course in Pennsylvania. It also was the site of last year's win.
"A funny story, but when the trophy was shipped here, the person at Alleghany put a message in with the package," Thompson said. "It said, `Please return with care to Alleghany Country Club.'"