Marguerite Reardon/CNET

Just when you think Apple can't lead another market, a retail research firm has come up with data to give the iPhone maker another victory.

According to RetailSails, Apple's brick-and-mortar stores generate more sales per square foot than any other U.S. retailer. The research firm, which examined the top 20 U.S. retail chains, said that Apple generated global sales of over $14 billion in its stores during the trailing four quarters. At the time of RetailSails' study, Apple had 327 stores with an average size of nearly 7,900 square feet. Thus, the research firm calculated that Apple makes $5,626 per square foot of floor space.

Apple beat out some retail juggernauts in the study. Jewelry retailer Tiffany & Co. came in second with $2,974 per square foot, while luxury retailer Coach came in third with $1,820 in sales. On the tech side, video game retailer GameStop took the fifth spot with $1,009 in sales per square foot. Best Buy was 10th, generating about $831 per square foot.

It didn't take long for Apple to become a brick-and-mortar giant. Earlier this year, the company celebrated the 10th anniversary of the opening of its first retail store. Since then, the outlets have cropped up around the world, with many of them showcasing a level of architectural design not easily met in the retail space.

But Apple isn't done. According to recent reports, the company is planning to build new showcase stores in both New York City and Santa Monica, Calif.

Last month, CNN reported that Apple had submitted plans to the Metropolitan Transportation Authority Board to build a new store in New York's Grand Central Terminal. If the deal is approved, Apple will pay about $1.1 million in rent per year for 23,000 square feet.

In addition, last week, a Santa Monica Planning Commission permit request surfaced, showing a store mockup that looked awfully similar to Apple's retail outlets. In the permit request, the retailer's name was kept anonymous, but based on the expected design--a 8,084-square-foot building featuring an all-glass roof and entrance way--speculation arose that Apple was behind it.