hamburger, such as the Ronald McDonald clown character designed by Willard Scott who first appeared on television in 1963, soon became a recognizable part of American culture. The burger also made appearances in underground comix such as Zap Comix#2 during the late 1960s, in which cartoonist Robert Crumb designed a character called "Hamburger Hi-Jinx". By the end of the decade, pop art was including the hamburger as an artistic element, appearing in the works of Andy Warhol (Dual Hamburger), Claes Oldenburg (Floor Burger), Mel Ramos (Vinaburger, 1965), and more recently, David LaChapelle (Death by Hamburger, 2002). An example of the popularity and identification that the burger enjoyed among the American public was the name of the Battle of Hamburger Hill, which occurred in May 1969 during the Vietnam War. Its name was inspired by the number of American and Vietnamese casualties, which made the scene resembles a "butcher". The hamburger was also the inspiration of Star Wars creator George Lucas's design for the Millennium Falcon ship. Hamburgers also appear in computer games, as in the case of BurgerTime, an arcade-style game created in 1982 by Data East Corporation. The hamburger also appears prominently on American television shows such as American Eats and Man v. Food. By the 1960s, American society had become highly motorized, largely due to the 1956 Federal Highway Act passed by President Dwight Eisenhower and inspired by the German Autobahn, as well as the impressive growth rates of American automobile manufacturers at the time. Due to the extensive use of cars at the time, hamburgers were often served at drive-ins, often by waiters known as carhops. Drive-in restaurants first appeared in the United States in the early 1930s, and gradually become a common sight across the country. The ability to serve hamburgers to customers in their cars was seen as a business opportunity by countless fast-food chains, especially McDonald's. The popularity of the hamburger grew rapidly among the American population during this period, and statistics indicate that the average American was eating three burgers per week. During the Cold War, the hamburger became a national symbol of the United States. As private outdoor social events, often held in backyards and featuring a barbecue, became more widespread during the mid-1950s, the hamburger gained a new culinary and social relevance in the country. By the late 1960s, hamburgers began to grow in size as various burger chains competed with