Smashburger has opened more than 200 restaurants in the past seven years.
Founder Tom Ryan told Nation's Restaurant News the fast-casual chain's success can be attributed to an unconventional marketing philosophy that relies heavily on social media and old-fashioned word of mouth.
Ryan said the chain still uses some radio and television advertising.
But Smashburger focuses heavily on events, such as when it offered a free sandwich to anyone with "burger" or "berger" in their name on National Cheeseburger day, he said.
Ryan said these events become a topic of conversation for bloggers and social media.
"From the beginning, we wanted Smashburger to be a defining brand for the next generation, and the marketing mix for how you engage them is different than for how you engaged the last generation," Ryan said.