As of Thursday, November 18, the Egg McMuffin has been around for half a century. McDonald's is celebrating the occasion with a steep discount. Via NPR:
The deal won't be on the table for long. The company says customers can only order the sandwiches from participating restaurants during "breakfast hours" and through the McDonald's app.NPR
According to the official McDonalds Egg McMuffin timeline, the sandwich started at a Santa Barbara location in 1971 thanks to Herb Peterson, a McDonald's franchise owner who was "partial to eggs benedict". After winning Ray Krok's approval, the sandwich rolled out nationally in 1975 and its success inspired a full-on breakfast menu two years later.