Wednesday, Sept. 18, marks National Cheeseburger Day, and many national chains and local burger joints are celebrating by giving away free burgers.

Since its origin in the early 1920s, the cheeseburger is one of America’s most beloved foods and certainly worthy of its own national (but unofficial) day.

“Fire up the grill or head to your favorite restaurant because today is National Cheeseburger Day!” proclaimed Punchbowl Inc., a Framingham, Mass., web-based company that offers party planning service.

“There are several theories about the origins of the cheeseburger,” the company says. “One story claims that the cheeseburger was created between 1924 and 1926 by a chef named Lionel Sternberger. As the story goes, a homeless man dining at Sternberger's restaurant in Pasadena, Calif., suggested the addition of a slice of cheese to his hamburger order. Sternberger complied, eventually added it to his menu, and the rest is history."

Here’s a rundown of the free cheeseburger deals being offered around the country for National Cheeseburger Day:

Ruby Tuesday: Free cheeseburger for the first 100,000 visitors to FunBetweenTheBuns.com.

Kings Bowl America (locations in Massachusetts, Illinois and Florida – find yours here): Free cheeseburger from noon-10 p.m.

Dog Haus: This Pasadena, Calif., eatery with two locations in the city is paying tribute to the cheeseburger’s roots by giving away a free mini cheeseburger to any customer from 11 a.m. to 5 p.m.

California Florida