CHICAGO — In 2009, burgers and sandwiches were the only broad food category to post servings growth at both quick-service restaurants and full-service restaurants, according to The NPD Group, a leading market research company.

During a year when restaurant traffic experienced consecutive quarterly declines, U.S. restaurant consumers gobbled-up more than 22 billion sandwiches, burgers, and wraps, according to NPD data.

“Sandwiches, burgers and wraps were the most resilient food category in this economic downturn,” said Bonnie Riggs, NPD restaurant industry analyst. “The reason is it’s one of the few categories that has mass appeal. Sandwiches, burgers and wraps are accessible, customizable, affordable, portable and can be dressed up, gourmet-style, or dressed down.”

Total servings of deli/other, chicken and wraps servings in 2009 were 12 billion, an increase of 1 billion servings since 2005, according to NPD’s CREST service, which continually tracks consumer usage of commercial and non-commercial foodservice. Total servings of burgers in 2009 were 9.3 billion, an increase of 800,000 servings since 2005.

All dayparts contributed to sandwich gains last year, but lunch contributed 48% of the growth in 2009, according to NPD’s CREST. Six out of 10 sandwiches and burgers are sold at quick-service restaurants.

“Moving forward, we’re likely to see more operators and chains jump on the sandwich, burger and wraps band wagon, capitalizing on the growth of this category,” Ms. Riggs predicted. “Considering how well-established the category is, it’s amazing to me to see that there still is room for more growth.”