The Egg McMuffin became McDonald's first nationally advertised breakfast item.
Herb Peterson created the sandwich in 1971 at a McDonald's franchise in Santa Barbara, California. It combined a toasted English muffin, a poached egg, Canadian bacon, and cheese. The product gave McDonald's a portable breakfast format that fit the chain's fast-service identity and could be prepared using existing restaurant equipment.
The Egg McMuffin initially appeared as a local test before McDonald's expanded breakfast nationally in the United States in 1975. Its success helped change the public perception of McDonald's from a restaurant mainly associated with lunch and dinner into an all-day food brand with a distinct morning occasion.
The product is sometimes confused with later breakfast launches such as the McGriddle, which debuted in 2003. The Egg McMuffin came decades earlier and became the signature visual and menu symbol of McDonald's breakfast branding.