Gasoline sales are increasingly important, helping to draw customers into the stores. Just a few decades ago, gas stations sold most of the nation's gas. Now convenience stores sell 80 percent of all fuel sold in the United States.

At a time when demand is growing, Maryland is seen as underserved, Lenard said. With 1,859 convenience stores, up from 1,781 five years ago, the state has one store for every 3,165 people, compared to the national rate of one store per 2,100 people, he said.

That means competition for prime sites, from high visibility corners to spots along major thoroughfares, said Geoffrey L. Mackler, a principal in Baltimore with H&R Retail, a real estate broker focused on retail properties.

"It's opportunistic," he said. "The real estate is expensive and scarce, but the appetite is definitely there for the right piece of property."

Royal Farms, which opened its first store in 1959 in Baltimore selling milk, is building nine stores this year. A new location opened in Eldersburg in Carroll County, with additional locations slated through the end of the year in Aberdeen, Pulaski Highway in East Baltimore, Hunt Valley, Pasadena and Queen Anne.

CEO John Kemp recently told CSP TV, an online news outlet for convenience store retailers, that the chain's growth strategy is to "pretty much just plod along. We'd like to build anywhere from six to 10 stores a year. Some years we've done less and some years, probably the last two years, we've probably done a little more."

Royal Farms' newest store format offers fuel, a car wash and carry-out food that includes deli sandwiches and an assortment of beverages such as iced tea, lemonade and milkshakes in addition to the signature fried chicken.

"The chicken program has been around many, many years, and it seems to keep on growing year after year," Kemp told CSP TV.

Kemp was not available for an interview last week.

7-Eleven also has aggressive plans for the Baltimore area as part of a new rapid expansion strategy. The chain, which opened more than 1,000 stores in the United States and Canada last year, plans to open eight to 12 new stores a year in the Baltimore area. Twenty-five stores opened in Maryland last year, including five in Baltimore county or city, and 7-Eleven plans to open 19 Maryland stores this year, including seven in Baltimore county or city.

"Baltimore is one of the markets where we are expanding," along with key growth areas of New York City, Washington, central and southern Florida, Chicago and the west coast, said Margaret Chabris, a spokeswoman.

Chabris said 7-Eleven began positioning itself for growth in the late 2000s when real estate values fell. The company was well positioned financially to build new stores as other retailers pulled back on growth plans.

Convenience chains also have benefited by entering urban markets left under-served by supermarkets, Mackler said. And residents have embraced them.

"In some neighborhoods where there is a food desert, they use 7-Eleven and pharmacies as their grocery store," he said.

Some shoppers are willing to pay the higher prices on staples such as milk and cereal, preferring to go to niche grocers such as Trader Joe's for specialty items.

"People are paying up," Mackler said. "Time and convenience are the most valuable commodities people have today."