National Cheeseburger Day is September 18, and to celebrate, major chains across the country are giving away free food. McDonald’s if offering a free cheeseburger though their app with a $1 minimum purchase. Dairy Queen keeps it simple with $1 off any Stackburger. Jack in the Box is celebrating with a $2 Jumbo Jack Cheeseburger. Smashburger is keeping the party going my offering a BOGO offer on September 19. Who makes your favorite burger?