Burgers are big business. The top 75 limited-service burger chains generated sales of more than $65 billion in 2010, according to Technomic. While the big three—McDonald’s, Burger King and Wendy’s—accounted for the majority of those sales, up-and-comers such as Shake Shack, Five Guys and Smashburger are increasing their share with burgers that promise more freshness and flavor, along with a touch of nostalgia. Non-commercial operators also are feeding the buzz, creating innovative burgers by using nontraditional fillers between the buns.

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