The McDonald brothers renamed their restaurant simply McDonald's in 1948.
Richard and Maurice McDonald opened their original drive-in in 1940 as McDonald's Bar-B-Q. After several years of operation, they recognized that barbecue meals and carhop service created delays and complexity. In 1948, they closed the restaurant for several months, reduced the menu, and reorganized food preparation around speed and consistency.
The redesigned restaurant focused on hamburgers, fries, and milkshakes. Customers ordered at a counter instead of from carhops, and the brothers used specialized workstations to assemble meals quickly. The system became known as the Speedee Service System and influenced the development of modern fast food.
The 1948 date is often confused with later milestones. Ray Kroc did not open the first McDonald's franchise until 1955, and the McDonald's Corporation was not established until 1955. The name change therefore belongs to the brothers' original operational transformation, before the national chain expanded.