American Elana Meyers had put her sled in front by .11 of a second going into the fourth run, but Humphries turned in the best time in the concluding trip down the sliding course. The American sled had the third quickest time in the final run, but it was not good enough.
The Canadians won by .10 of a second.
As a consolation prize, the Americans earned both the silver and bronze medals, giving the United States the lead in the overall Olympics medal race with 23.
Meyers was joined in the sled by Lauryn Williams, who became the fifth athlete in the history of the Olympics to win a medal in both the Summer and Winter Games. Williams was the 100-meter silver medalist in Athens in 2004.
The bronze medal went to Jamie Gruebel and Aja Evans, who finished .90 of a second behind their American teammates.
Notable deaths of 2014 [PHOTOS]
Julius Randle breaks leg during NBA debut