After two and a half periods of tightly contested action, Monique Lamoureux-Morando knotted the score at 2-2 with just under seven minutes remaining in regulation.
Even though Canada had numbers late in the overtime, they couldn't capitalize on the power play, and the extra-session went scoreless.
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And after Lamoureux-Davidson put the US ahead 3-2, 20-year-old goaltender Maddie Rooney denied the veteran Meghan Agosta to clinch the USA's first Olympic gold since Nagano 1998.