Hamburger, basically ground up beef, can be cooked both medium or well done. Because of the process involved in making hamburger & its relatively large surface area for bacteria to grow on, eating rare hamburger is a no no. One thing has always puzzled me though. Why to Americans call it hamburger when its obviously beefburger?

Hamburger Internal Temperature
Not recommended
150 degrees
160 degrees
Cooking - Hamburger Temperatures