That's a good question, but I call them beefburgers so I have no idea. Hamburgers are those things that taste like spam

I believe it originated in Hamburg, Germany. Just like the Frankfurter originated in that country.

"Hamburger also refers to the cooked patty of ground meat by itself. The patty alone is also known as a beefburger, or burger. Adding cheese makes it a cheeseburger. Hamburger is actually a distinct product from ground round and other types of ground meat. However, ground beef of any form is often commonly referred to as "hamburger." A recipe calling for 'hamburger' (the non-countable noun) would require ground beef or beef substitute- not a whole sandwich. The word hamburger comes from Hamburg steak, which was named after the German city of Hamburg. Contrary to what folk etymology might lead one to believe, there is no actual 'ham' in a hamburger." "According to the American Heritage Dictionary, the term "hamburger" comes from Hamburg steak, which was first recorded in English in 1884 but was probably used much earlier. A form of pounded beef called "Hamburg Steak" was common in Hamburg in the middle of the 19th century. The recipe was brought to North America by the large numbers of people immigrating from Germany at the time, many of whom passed through the port of Hamburg. There is indirect evidence for its use on an American menu in 1836. The form hamburger steak first appeared in a Washington state newspaper in 1889. The first recipe close to the current idea of a hamburger, using ground beef mixed with onion and pepper dates from 1902. The Oxford English Dictionary of 1802, on the other hand, defines "Hamburg Steak" simply as cured beef. In a time without refrigerators, when it took weeks to travel from Europe to the USA, cured meat was a standard food for poor US immigrants, who often started from Hamburg (which was and is the biggest German seaport and one of the biggest in the world). In a tween deck, where cooking is nearly impossible, cutting tough cured beef into pieces and putting it between slices of bread may suggest itself." Source and further information: http://en.wikipedia.org/wiki/Hamburger

Al Gore has probably claimed to have invented the name. Add that to the list of his assaults on reason.