Hamburg Steak
In the late eighteenth century, the largest ports in Europe were in Germany. Sailors who had visited the ports of Hamburg, Germany and New York, brought this food and term "Hamburg Steak" into popular usage. To attract German sailors, eating stands along the New York city harbor offered "steak cooked in the Hamburg style."
Immigrants to the United States from German-speaking countries brought with them some of their favorite foods. One of them was Hamburg Steak. The Germans simply flavored shredded low-grade beef with regional spices, and both cooked and raw it became a standard meal among the poorer classes. In the seaport town of Hamburg, it acquired the name Hamburg steak. Today, this hamburger patty is no longer called Hamburg Steak in Germany but rather "Frikadelle," "Frikandelle" or "Bulette," orginally Italian and French words.
According to Theodora Fitzgibbon in her book The Food of the Western World - An Encyclopedia of food from North American and Europe:
The originated on the German Hamburg-Amerika line boats, which brought emigrants to America in the 1850s. There was at that time a famous Hamburg beef which was salted and sometimes slightly smoked, and therefore ideal for keeping on a long sea voyage. As it was hard, it was minced and sometimes stretched with soaked breadcrumbs and chopped onion. It was popular with the Jewish emigrants, who continued to make Hamburg steaks, as the patties were then called, with fresh meat when they settled in the U.S.
The Origin of Hamburgers and Ketchup, by Prof. Giovanni Ballarini:
The origin of the hamburger is not very clear, but the prevailing version is that at the end of 1800' s, European emigrants reached America on the ships of the Hamburg Lines and were served meat patties quickly cooked on the grill and placed between two pieces of bread.