Both racers had already locked up their overall and discipline titles in recent weeks before adding convincing wins at the World Cup finals.
Shiffrin won her seventh slalom of the season, a personal best for the American. Holding on to a commanding first-run lead, Shiffrin won by a massive 1.58 seconds over Wendy Holdener of Switzerland. Olympic slalom champion Frida Hansdotter of Sweden was another 0.01 behind in third.
“It was so much fun. This is how I want to feel every race. In the second run, it’s my dream of skiing like that,” said Shiffrin after her 32nd victory in the discipline and 43rd overall.