DENVER -- They've closed up shop in Colorado, or are getting ready to: Comp USA, Linens 'n Things and now Circuit City.

Many business owners, who operate stores adjacent to the big boxes, are beginning to wonder how long the big boxes will remain empty.

Susan Hartley owns Salon on the Boulevard, which sits across the street from the Circuit City on South Colorado Boulevard. She said her main concern is an empty parking lot with no security.

"Seedy people come by, drug deals start happening and that's our greatest concern," Hartley said.

"It's a legitimate concern," said professor Jeffrey Engelstad of the School of Real Estate in the Daniels College of Business at the University of Denver.

Engelstad said when you take away 50,000 to 100,000 square feet of retail space you leave an incredible void.

"I'll tell you who it really affects -- the small retailers who are in there together with the big box stores, because the big box stores drive the traffic," Engelstad said.

At 92nd Avenue and Sheridan Boulevard, a Circuit City, hosting a close-out sale, sits right next door to an empty Comp USA. When asked if she was worried about blight, one shopper told 7NEWS that her concern was more basic.

"I'm worried that we only have one electronic store left. What's going to happen to prices if they don’t have anyone to compete with?" the shopper asked.

Many people wonder how long some of those big box stores will remain empty.

Engelstad said sometimes communities can find another use for an empty big box store.

"Some have been turned into recreation centers or community centers," he said.

But more often, the big boxes sit empty until they're redeveloped.

Sometimes that can be a long time.

In Westminster a former Builder's Square at 92nd Avenue and Wadsworth Boulevard has sat empty for more than a decade.

The professor said, "I think the problem with big box stores is going to be something that is going to become more pronounced in 2009 and we probably won't see a turnaround until late 2010."