It's stated in the passage that Americans..........

Hamburgers are an American speciality which are increasingly gaining in popularity all over the world. They are named after the city of Hamburg in Germany, and were introduced into America by the early German immigrants. They are made from beef, so the name has nothing to do with “ham”, which is made from pig meat. The Americans often simply call them “burgers” and have even formed words like "cheeseburger" and “eggburger”, depending on the extra ingredients included with the burger.