We've used our Canadian membership card in US Costco's without issue.

FYI.........you'll usually find the lift tickets located in the middle of the stores floorplan, placed at the ends of the aisles. You need to bring one of the cardboard hang tags on the display to the front counter, pay, and then the cashier gives you the ticket.

By the way it feels like -43 here in YYC today according to the various forecasters. Supposed to go up to -1 next week though.