We have always made every one of our hamburger patties ourselves using only whole chucks from premium cattle selected especially for In-N-Out Burger. We pay a premium to purchase fresh, high-quality beef chucks. We individually inspect every single chuck we receive to make sure that it meets our standards. Then our highly skilled, in-house butchers remove the bones. We grind the meat ourselves and make it into patties ourselves. These steps enable us to completely control the patty-making process and be absolutely certain of the quality and freshness of every patty we make. We’ve always made our hamburger patties this way.
Best thing is they are very reasonably priced!
Just checked their site - there aren’t any within 150 miles of me :-(