Amid the devastation caused by Superstorm Sandy, Dunkin' Brands (DNKN) is working hard to keep the lights on.

Residents along the East Coast are flocking to Dunkin' Donuts locations, many of which are open while just about everything else seems closed. People are posting photos of Dunkin' Donuts lines on Twitter, including this one reportedly showing 100 people waiting. "The lines at every Dunkin within a 10 mile radius are insanely long," wrote someone else. There were also crowds at McDonald's (MCD) and Burger King (BKW) restaurants.

"Very few restaurants have closed," a spokeswoman for Dunkin' Brands told Bloomberg. "Any closures have been due largely to power outages or as a result of evacuations in affected areas. The majority of our restaurants are open and taking care of their customers."

Nearly all Dunkin' locations are operated by franchisees, and it's up to the individual franchisee to decide whether to open. Bloomberg reports that about 100 stores ended up closing.

Working to stay open in a storm is smart business and a community service. For Dunkin', however, it's also hugely important to the bottom line. The company's locations are heavily concentrated on the East Coast, and a storm of Sandy's magnitude will likely be a hit to sales this quarter. The company relies on its U.S. doughnut shops for some 75% of total sales, reports Investor's Business Daily.

Dunkin' has been slightly growing sales. For the third quarter ended Sept. 29, Dunkin' said that same-store sales at its U.S. doughnut shops grew 2.8%.

After falling below $26 at the start of the year, Dunkin' shares have risen to nearly $31.

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