McDonald's first national breakfast sandwich, introduced in 1972, was the Egg McMuffin.
Herb Peterson, a McDonald's franchisee in Santa Barbara, California, developed the sandwich with his assistant Donald Greadel. It used an English muffin, a round egg, Canadian bacon, and cheese, creating a portable breakfast item that could be prepared quickly.
The Egg McMuffin helped McDonald's establish breakfast as an important part of its brand and daily business. After local testing, the sandwich expanded nationally in 1972 and became one of the company's signature products.
It is sometimes confused with the McGriddle, which arrived much later and uses griddle cakes. The Egg McMuffin's importance in branding comes from making McDonald's recognizable as a breakfast restaurant as well as a burger chain.