Blanks shot a 3-under 67 on the difficult Shaughnessy Golf & Country Club course in a round that featured an eagle at the par-5 seventh.
Ernie Els, one of a handful of players who made the long trip to Vancouver from England after competing in last week's British Open, was part of a large group at 68.
Els was tied for second with Bill Lunde, Kevin Kisner, Woody Austin, Bo Van Pelt, Matt McQuillan, Paul Goydos, Jimmy Walker, Ben Martin and Aaron Price.
Rickie Fowler and Lucas Glover, both of whom challenged for the British Open crown before it was won by Darren Clarke, each had a 69.
John Daly, who has played in 13 tournaments this year and finished only four of them, opened with a 70.
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