1921: The first White Castle restaurant opens with just four menu items – hamburgers, Coca-Cola, coffee and apple pie.

1924: White Castle becomes one of the first companies to provide health insurance for team members.

1927: Founder Billy Ingram invents the idea of restaurant “carry out” and unveils the tagline “Selling ‘em by the Sack.”

1934: White Castle moves its home office from Wichita, Kansas, to Columbus, Ohio.

1947: Cincinnati Castle operator Earl Howell introduces the idea of adding five holes to the patty, enhancing the flavor and helping it cook faster.

1961: White Castle becomes first fast-food chain to sell one billion burgers.

1962: Forty-one years after opening, White Castle adds its first new menu item, the cheeseburger.

1970: White Castle introduces “Hamburgers to Fly” program, shipping hamburgers via air express to those who live far from a White Castle restaurant.

1986: White Castle introduces breakfast sandwiches.

1987: White Castle makes frozen sliders available in grocery stores across the U.S.

1990: White Castle creates turkey stuffing recipe using 10 Original Sliders.

1991: White Castle accepts reservations for Valentine’s Day dinners.

1997: Gerard Hogan publishes “Selling ‘em by the Sack.”

2001: White Castle inducts first class of Cravers Hall of Famers.

2001: White Castle debuts Crave Case packaging containing 30 sliders.

2004: White Castle introduces the Crave Crate containing 100 sliders.

2014: White Castle offers breakfast 24 hours a day.

2015: White Castle introduces Veggie Sliders.

2018: Impossible Slider debuts at White Castle, the first fast food chain to offer the burger made from plants.

Source: White Castle