The hot dog’s ancestor is the frankfurter, a long thin sausage from the German city of Frankfurt that has been made there for centuries. German immigrants brought their frankfurter recipes with them when they moved to the United States in the 1800s. By the 1860s, German-American street vendors were selling them from carts in New York.
Nobody knows for sure who first put the sausage inside a bun. One legend says a vendor used gloves to hand customers his hot sausages, then started running out of gloves - so he asked a baker to make long soft bread rolls to hold them instead. Another story credits the wife of a Bavarian street vendor in St. Louis with the same trick.
The name “hot dog” came later, around 1900, supposedly as a joke that frankfurters looked like the long-bodied dachshund breed of dog. Some early menus even called them “dachshund sausages.” Today Americans eat around 20 billion hot dogs a year - that’s 60 per person, on average.