If you've ever eaten a hamburger at a fast-food restaurant, White Castle deserves at least some of the credit.

The Columbus, Ohio-based chain is famous for its cheap, small burgers. It's also widely regarded as the first fast-food hamburger chain in the United States.

White Castle started in 1921 in Wichita, Kansas — decades before competitors McDonald's or Restaurant Brands International's Burger King arrived on the scene. White Castle laid the groundwork for those chains, and it played a key role in making the hamburger synonymous with American cuisine.

McDonald's and Burger King grew quickly, from regional, to national, to international chains in a matter of decades. White Castle, on the other hand, stayed small. Today, there are about 370 White Castle restaurants in 13 states.

Throughout its nearly 100-year history, White Castle has been opposed to franchising its business, a mechanism that fueled other fast-food companies' growth.

CEO Lisa Ingram is the fourth generation of her family to run the chain. She acknowledged that other business models would have led to faster growth.

"But you have to give up control and you have to give up the ownership of the customer and the ownership of the team member," she said. "And that's just not something that we have ever really been interested in doing."

White Castle is testing the waters outside its Midwest and Northeast stronghold, with restaurants in Nevada, Arizona and China. The restaurants in Nevada are licensed, but White Castle said that won't be its model for future growth.

"We still keep coming back to [the fact] that this model has worked well for us for almost 100 years and that we believe it's a good model for us to continue into the future," Ingram said.

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