Frankfurter refers to a highly seasoned sausage made of a mix of pork and beef. In the United States, the term frankfurter commonly refers to a hot dog. Frankfurters usually comprise of thin reddish brown sausages preserved by smoke or chemicals and stuffed in casing; people usually eat them with bread. Frankfurters increased in popularity in the US around 1900. Coney Island opened the first hot dog stand in 1916. Today, frankfurters commonly get associated with outdoors events such as barbecues, picnics and sporting events. German and Austrian frankfurters have many varieties. Sometimes people eat frankfurters warm with sauerkraut; in other cases, they eat them cold with potato salad. Most commercial frankfurters contain nitrates or nitrites to prevent botulism-causing bacteria from growing.