Scranton, 38, who had reconstructive shoulder surgery in 1996, closed with a 2-under-par 70 to match Hjorth at 13-under 275 on The Club at The Strand. Hjorth, 26, shot a 64.
On the second playoff hole, the par-4 10th, Hjorth left her approach shot right of the pin, just off the green, while Scranton knocked her approach within 15 feet. Hjorth had a 6-footer for par, but the ball broke right across the hole at the end, leaving Scranton to tap in a 1-foot par putt for the victory.
Both players birdied the first extra hole, the 18th, with Hjorth making a 7-foot putt, and Scranton following with a 4-footer to extend the playoff.
Scranton earned $127,500 for her third tour title. She also won the 1991 du Maurier Classic, and the 1992 Los Coyotes LPGA Classic. Hjorth, a two-time winner last season, earned $79,129.
Scranton rallied to tie for the lead with a birdie on No. 11 and an eagle on No. 12 back-to-back par-5s then took the lead with a 4-foot birdie putt on No. 16. But she left her approach shot short of the green on No. 18 and missed an 8-foot par putt.
Third-round leader Jen Hanna three-putted the par-3 17th for a bogey to end her chances of becoming the first rookie to win her first event as an LPGA Tour member since 1951. She shot a 74 to tie for eighth at 277.
Australia's Jan Stephenson, 48, won the $500,000 Evista Legends Series, a competition that started in 1999. Stephenson, who won her first professional event in Naples in 1976, earned $125,000, her biggest official paycheck ever. The Legends series is for players age 40 and over.
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