The frankfurter, or hot dog, has deep roots in Germany. Frankfurt claims the sausage was invented there in 1487. These early sausages were made of lean pork and kept in sheep's intestine casings. They were brought to the United States in the 1860s by German immigrants who sold them from pushcarts in New York City. The transition to the 'hot dog' as we know it happened on Coney Island, where Charles Feltman opened the first hot dog stand in 1867. The bun was introduced to allow customers to eat the hot sausage without burning their hands. Today, hot dogs are a staple of American culture, with over 20 billion consumed in the U.S. every year.