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

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 promotions or otherwise get a boost — but not so much at Costco.

The wholesale club has a longstanding policy of closing US stores on seven holidays, spaced throughout the year. Costco still runs Labor Day sales, you just can't get the deals at the warehouse on Labor Day itself.

"We feel it is important for our employees to enjoy these holidays with their families/friends," CEO Ron Vachris told Business Insider via email. "That is the reason we close on these days."

Costco's decision to close for a week's worth of days each year contrasts with most national chains' holiday schedules, which typically close for Thanksgiving and Christmas. Home improvement retailer Lowe's also closes on a third day: Easter Sunday.

In addition to being posted on giant metal signs at warehouse entrances, the list of days is enshrined in the Costco employee agreement, which is negotiated every few years between workers and leadership.

Former CFO Richard Galanti told Business Insider the employee agreement is generally similar to the labor contract Costco has with employees at locations with Teamsters union representation.

And while US warehouses do hundreds of thousands of dollars in sales every day, Galanti said the cost of shutting down was never a consideration during his tenure with the company.

"We never looked at the math," he said. "If it's the right thing to do, we do it."

At the same time, Costco has such strong loyalty among its members that a holiday's sales don't entirely disappear — they shift.

"You may lose a little business that day, but you're gonna get most of it back the day before or after," Galanti said.

Here are the holidays on which US Costco warehouses are closed:

• New Year's Day
• Easter Sunday
• Memorial Day
• Independence Day
• Labor Day
• Thanksgiving Day
• Christmas Day