Outlet malls, which offer savings on designer goods in an open air setting, are expanding their footprint.

When Gloucester Premium Outlets opens in August in Blackwood, it will be the 69th outlet center in the United States for Simon Property Group.

The company's portfolio has grown steadily over the last three decades, with at least one or two outlets opening every year since 1995. That trend is likely to continue, says Stephen Yalof, chief executive officer of Simon Premium Outlets.

"We're building new shopping centers with more demand, both from the consumer end and the retailers' end," he said. "People love them."

Simon owns the largest and most profitable outlet in the country: Woodbury Common Premium Outlets. Located about 50 miles northwest of New York City, it measures nearly one million square feet and boasts 300 brands. Simon also owns 16 international outlet centers, including nine in Japan, three in South Korea, one in Malaysia, and one outside of Mexico City.

In the first quarter, Simon reported a 96 percent occupancy rate at its domestic outlets, about the same as last year. But sales per square foot were $621, up from $576 in the January-to-March period in 2014.

"They provide tremendous value - it's that simple," David Cordish, chairman of Cordish Cos., which developed Walk in Atlantic City, said of the popularity of outlets. Pennsylvania Real Estate Investment Trust (PREIT), which owns several malls in the region, is redeveloping the Gallery at Market East and renaming it the Fashion Outlets of Philadelphia.

"Off-price apparel chains, outlet malls, food, and entertainment are the fastest-growing segments in retail, fueled by consumer spending habits during the recession," said Joe Coradino, CEO of PREIT.

"It's destination shopping for value," said Simon's chief operating officer of premium outlets, Mark J. Silvestri. "It's almost a treasure hunt. You're going out there and don't know what you are going to find."

Jasmine Santiago 27, of Reading, found several bargains recently at Philadelphia Premium Outlets, off Route 422 West in Limerick. She bought seven pairs of shoes at Aldo during a two-hour jaunt with boyfriend Marquis Jackson, 33. The couple also bought clothes at Bebe, Polo Ralph Lauren, and True Religion. The total tab was $600 to $700.

"We were rushing around, but we got what we wanted," said Santiago, a home equity specialist.

Philadelphia Premium Outlets opened in November 2007 and completed a 120,000-square-foot expansion less than a year later. It now has 150 stores - including Michael Kors, Neiman Marcus, and Vera Bradley.

Yalof, who worked previously as senior vice president of real estate at Polo Ralph Lauren, said an outlet is a collection of manufacturers selling directly to the consumer, which allows significant markdowns on designer and house brands because there is no middle man.

Many stores at an outlet are smaller than those in an enclosed mall, and an outlet center has no anchor department stores.

Simon is considered the pioneer of the outlet. It opened the first one, Liberty Village Premium Outlets, in Flemington, N.J., in 1981 - and that started the outlet mall evolution.

"We offer three things: value, fashion, and the customer experience," he said. "If you fail one of those, you may lose the customer for good."

Yalof said making the shopper comfortable with amenities, such as valet parking and places to sit and relax, or eat, was key.

"We encourage them to spend more time there," Yalof said. "It is not based on need, but more for leisure shopping - people make a day of it, so we put in landscaping and fountains."

Allison Hoffman, 28, a teacher from Shenandoah, Pa., drove 1 hour and 45 minutes to get to Philadelphia Premium Outlets last week on her way to Philadelphia International Airport.

"Everyone told me I had to stop here," said Hoffman, as she shopped at the Gap.

Outlets are often located away from enclosed shopping malls. Case in point: King of Prussia Mall and Philadelphia Premium Outlets, both owned by Simon, are 18 miles apart.

"The regional mall serves all things to all people - it's a community place, it's shopping everyday," Yalof said. "They go to the premium outlets four or six times a year. It's more destination shopping.

"Spacing has to do with large department brands in the enclosed malls," Yalof said. "Manufacturers are selling wholesale to Macy's. They don't want to be across the street from Macy's. They want to reach as many consumers as possible with different venues."

Silvestri said that preferred outlet sites had great access and visibility off major highways and "areas with families on a budget looking for brands at a value."

The location for Gloucester Premium Outlets, off Route 42 at Exit 7-A in Blackwood, Gloucester Township, satisfied all the criteria for Simon.

"That whole side of the Delaware River was lacking that type of [outlet] venue," Silvestri said. "Gloucester [Township] is right in the middle. We want to capture transient customers heading from Philly to Atlantic City."