A burger is a burger—until, of course, you really start thinking about them, which I often do. The basic tenets of a burger should first be defined as ground beef, cooked somehow, and served on bread. Where the burger chefs of America and beyond have taken the dish from that starting point has become a thing of legend. It seems every cooking method and condiment has been explored, generating legions of absurd cheeseburger concoctions on menus across the land.
But to me, hamburger architecture is paramount. The burger should not be a complicated thing; like a haiku, the best examples benefit from a limitation of form. Simplicity trumps all, and fewer ingredients and condiments involved allow the beefiness of the burger to shine. In the interest of creating the perfect burger, less here is far more.
This list represents the most important styles that exist in the U.S. today—the ones I believe should be sought out, appreciated, and consumed (with the exception of the Mini Burger, which should be avoided). These burgers are the jumping off point for so many other variations on a theme, and to be honest, the burgers you're really looking for. They are the ones you will invariably return to—your daily beaters, the platonic ideal.
Here is a taxonomy of burger styles in America.