What to know about the U.S. Postal Service’s past, possible future

The U.S. Postal Service is celebrating its 250th anniversary this weekend, and you won’t have to check your mailbox for the invite.  The agency’s semiquincentennial will be marked by an event at the Smithsonian’s National Postal Museum in Washington, D.C., on Saturday, two and a half centuries since its founding. Two newly announced commemorative stamps