Most national retailers close on 2 holidays. Costco shuts down for 7.

Costco's holiday closing dates are posted at the front entrance of a Costco warehouse.Dominick Reuter/Business InsiderNo Costco for you on Labor Day - the warehouse has long closed US stores on seven holidays each year.The retailer's former CFO Richard Galanti told Business Insider the cost was never a consideration."We never looked at the math," he said.If there's one thing Americans love to do with their free time, it's shop.Retailers often treat their customers' days off as an occasion to run