PHILADELPHIA—As retailers continue to go vertical, look for a major city promoting its downtown—along with a baby boom. "We've been putting our resources together, including everything from event marketing to public relations, helping retailers from beginning to end," says Anne Nevins, vice president of market development for the Philadelphia Industrial Development Corp.

In the past decade, Center City's population has grown by 10%, with some 179,000 residents calling the trade area home, the city says. Greater Center City experienced a 53% increase in median household income between 2000 and 2010. According to the just-released Center City District annual retail report, demand for goods within one mile of City Hall reached $710.9 million this past year, up from $491.5 million in 2010. Adding to that market is a growing tourism base, with three new hotels already under construction and a fourth slated to begin building by year-end.

"We are looking for new and better retail to supplement what we have," says Michelle Shannon, VP of marketing and communications for Center City District/Central Philadelphia Development Corp. "There are people who have an outdated perception of the city."

Brian Flanagan, chief of staff to the deputy mayor for economic development for the City of Philadelphia, says the city is focused on two main drags—Market and Broad streets. In partnership with the Center City District, the city also looks to meet with developers and investors to tout the central business area. "There seems to be a real retrenchment into core investments," Flanagan says. "Philadelphia is positioned well."

Existing retail, including more than 125,000 square feet that has opened this year, has included a mini-British Invasion with Jack Wills, Dr. Martens, and Barbour. Brands such as Apple, Athleta and the Children's Place have enjoyed strong sales, the group says. Eateries also are expanding, including Starr Restaurants' Il Pittore, its 19th location in the city.

Perhaps most appealing is the surprising increase of children living Downtown, resulting from urban professionals declining to move to the suburbs once they start a family. In the three catchment areas corresponding to Center City Core, the number of school-age children rose 15.7% in the last decade. And with 20,553 children born to Greater Center City parents between 2000 and 2010, the city expects a 66% potential increase in school-aged children.

Many Center City residents don't even own a car, so accessing the malls outside of town isn't an option. "What sets us apart is the host of entrepreneurs with boutiques that offer the unique," Shannon says. "Philadelphia is made up of neighborhoods, not just residential but of retail. That's our strength against the suburbs."