the May 15, 1940, opening of a restaurant named McDonald's along U.S. Route 66 in San Bernardino, California. After analyzing their sales, the brothers discovered that, to their surprise, 80% of their revenue was coming from selling hamburgers. The menu initially featured 25 different dishes, the majority of which were barbecued. Through their new restaurant, the McDonald brothers introduced the notion of fast food to parts of the Western United States by 1948. From the beginning, McDonald's focused on making hot dogs and hamburgers as efficiently and quickly as possible. During the 1940s, simple and formative concepts took root at McDonald's, including the preparation and service of burgers in just one minute and the ability for customers to eat in their own cars in a drive-in style. All the while, the restaurant was trying to further develop a hamburger that was inexpensive enough to be within the economic reach of most Americans. By the 1950s, the concept of drive-in style service had become firmly established and hamburgers and cars had become closely connected in the minds of many Americans. It was now not only possible for a customer to purchase a hamburger without getting out of a car, and a customer also no longer needed to wait to be served. The McDonald brothers built upon the achievements of their original San Bernardino restaurant when in 1953 they began franchising their now famous chain restaurants, starting in Phoenix, Arizona, and Downey, California (the latter of which is still in operation). Later, Ray Kroc opened one in the northwest Chicago suburb of Des Plaines, Illinois on April 15, 1955, which has now been converted into the McDonald's Museum. It is noteworthy that the original McDonald's mascot was a hamburger faced cook called "Speedee" that would serve as the iconographic identity of the company until being replaced by the clown Ronald McDonald in 1963. The McDonald brothers intensively studied the existing kitchen protocol of their restaurants in an effort to improve them. They looked at different options that could increase the speed of cooking hamburgers, designing and patenting special grills that had a higher output, made their cutlery and other kitchen utensils disposable, and introduced dishwashers that reduced the costs of water, soap, and labor. The brothers also created a detailed system for operating each kitchen throughout the franchise in a similar and largely standardized manner, as well as recruiting adolescents as employees