Diggins rounded out her time in Toblach with two sixth place finishes in the seven-leg race.
Her results were enough to secure fourth place overall in the competition behind two skiers from Norway and one from Finland.
Parkite Rosie Brennan is the next best-scoring American, sitting in 27th place after the first four days of competition.
The Tour de Ski race will travel south in the Dolomites to Val Di Fiemme for the final three legs of racing this weekend.
