What's open on Presidents Day? From Costco to the U.S. Postal Service, here's what's open and closed.

Presidents Day is celebrated in the U.S. on the third Monday of February, a day set aside to commemorate the birthdays of both President George Washington and President Abraham Lincoln. 

Over the years, the federal holiday has shifted into a commercial event, with many retailers offering sales on Presidents Day to tempt shoppers to open their wallets after the Christmas holidays. 

That occurred after Presidents Day was shifted permanently to the third Monday in February in the early 1970s, creating a permanent three-day weekend. As a result, sales campaigns soared, historian C. L. Arbelbide wrote in the National Archives' Prologue magazine in 2004.