While the modern hamburger is an American icon, its roots lie in Hamburg, Germany. In the 19th century, 'Hamburg Steaks'—patties of minced beef—were a popular meal for German immigrants. The transition from a plate-served steak to a bun-enclosed sandwich happened in the late 19th-century United States. Multiple people claim the invention: Charlie Nagreen (who sold meatballs in bread at a fair so people could eat while walking), the Menches brothers, and Louis Lassen of Louis' Lunch in New Haven. The 1904 St. Louis World’s Fair is often cited as the event that launched the hamburger to national fame. Today, it is estimated that Americans consume over 50 billion burgers a year.