Which McDonald's restaurant opening in 1955 is commonly treated as the start of the modern franchise company?

The Des Plaines, Illinois, restaurant opening in 1955 is commonly treated as the start of the modern McDonald's franchise company.

Ray Kroc opened the restaurant on North Lee Street in Des Plaines on April 15, 1955. Kroc had become involved with the McDonald brothers after seeing the efficiency of their San Bernardino operation and later built a large franchise network around the system.

The distinction between Des Plaines and San Bernardino matters. Richard and Maurice McDonald opened the original McDonald's restaurant in San Bernardino in 1940, while the Des Plaines location was Kroc's first McDonald's franchise and the foundation of the later corporate expansion.

The Des Plaines building was eventually preserved as a museum, although the site was later affected by flooding. Its historical importance comes from franchising and branding, not from being the first McDonald's restaurant ever opened.