<P> 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 each other, resulting in Burger King launching the Whopper and McDonald's launching the Quarter Pounder . As the race between the major chains grew more intense, the prices of their burgers increased, and the days when a hamburger could be bought for just a few cents were numbered . </P> <P> In the 1970s, major hamburger chains began to use considerable resources in marketing their products . They began to compete directly with each other through their advertising, much of which was comparative and often featured direct allusions and comparisons . The event came to be jokingly referred to as the "burger wars" by many Americans . By the end of the 1980s, the era of slogans in large chain restaurants had begun . </P> <P> The modern hamburger was developed in the United States, but by the end of World War II, around the middle of the 20th century, it began to spread to other countries as fast food became globalized . The main cause of this gradual globalization was the successes of the large restaurant chains . Their desires to expand their businesses and increase their profits resulted in them creating franchises around the world . McDonald's was among the very first of the burger chains to take the global establishment of its brand seriously, but it was not the only one . Wimpy began operating in the United Kingdom in 1954, 20 years before McDonald's began operation in the country, and by 1970 it had expanded to over a thousand restaurants in 23 countries . On August 21, 1971, in Zaandam, near Amsterdam in the Netherlands, Ahold opened its first European franchise . In the 1970s, McDonald's began to expand into Europe and Australia . In Asia, Japan saw the establishment of its own fast food chain in 1972: MOS Burger (モスバーガー, Mosu bāgā), an abbreviation of "Mountain, Ocean, Sun", which eventually became a direct competitor to McDonald's . All of its products, however, were variations on the burger adapted to the Asian world, including the teriyaki burger, takumi burger, and riceburger . In Hong Kong, Aji Ichiban competed with large chains before it spread quickly throughout Asia . One of the first hamburger vending machines debuted in Amsterdam in 1941 under the brand FEBO, its name derived from its original place of creation, the Ferdinand Bolstraat . </P> <P> At the same time the hamburger was growing in popularity around the world, it took on a variety of local features in different locations . Such examples of this include ground meat made from local animals, such as kangaroos in Australia, or Tex - Mex - style dishes like chilli con carne . </P>

Where did the hamburger make its international debut