Joshua Pauls added a goal and an assist for the U.S., while Steve Cash made 11 saves to get the shutout.
The Americans will face Russia in Saturday's gold-medal game at Shayba Arena after the hosts defeated Norway 4-0 in Thursday's other semifinal.
Corbin Watson stopped seven shots for Canada, which will play Norway for bronze on Saturday.
Thursday's result was a bitter pill to swallow for the Canadians, who were trying to become the first country to sweep men's, women's and sledge hockey at an Olympic and Paralympic Games.
Gold medallists in 2006, Canada was also looking to avenge a disappointing fourth-place finish on home soil in Vancouver in 2010 and was perfect through three round-robin games, outscoring the opposition 15-1.
The Americans, meanwhile, will play for gold for the second straight Paralympics after winning the tournament four years ago. The U.S. was upset by Russia 2-1 in their final group game here to set up a semifinal against their bitter rivals.
Canada came in having won the 2013 world championship and world sledge hockey challenge — with both victories coming over the U.S. — but lost two of three exhibition meetings with the Americans in the leadup to the Paralympics.
In other results, Toronto's Chris Williamson and guide Nick Brush of Panorama, B.C., won Canada's sixth alpine skiing medal of the games, claiming bronze in the visually impaired men's slalom.
Williamson finished in one minute 48.61 seconds, behind Russia's Valerii Redkozubov (1:43.21) and Spain's Yon Santacana-Maiztegui (1:46.82).
Kimberly Joines of Rossland, B.C., was awarded the bronze medal from Wednesday's women's sit-ski slalom. Joines had finished in the silver-medal position, but was bumped down a rank when Germany's Anna Schaffelhuber successfully appealed her disqualification and won gold.
It was a mixed day for Canada in wheelchair curling. Canada thrashed Slovakia 16-0 before losing 12-1 to Finland.
Canada finished the round-robin in second place at 7-2 and will face China in a semifinal on Saturday.
Canada is third in the overall medal standings with 10 medals (two gold, two silver, six bronze). Russia leads with 50 medals, followed by Ukraine with 14.