The hard-hitting 21-year-old from Thornhill, Ont., is the first Canadian male to get this far at Flushing Meadows since 1988, when Montreal's Martin Laurendeau did it.
With the win, the 15th-seeded Raonic lined up a meeting with third seed and Olympic gold medallist Andy Murray, who struggled to get past Spain's Feliciano Lopez 7-6 (7-5), 7-6 (7-5), 4-6, 7-6 (7-4) after nearly four hours of play.
Raonic moved quickly on Saturday, crushing the 32-year-old Blake with 28 aces in under two hours.
Raonic also broke Blake five times and fired 54 winners to ensure that he'll be playing in the deciding week of a major for the first time since the 2011 Australian Open.
Raonic swept the first two sets before Blake made a minor stand in the third. But the Canadian took command when the set went into a tiebreaker, serving out the win on his third of five match points.
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