Bigger, better, newer and farther out.

"We're sort of like locusts," says Lado. "We go, we use the housing, and then we're gone. You have places like Rochester, New York, that haven't grown in population, but their land mass has increased. Because it's like you abandon your inner ring, so you go to your next ring out."

Northglenn's original developer has followed generations of the trend. Its three-decade-old Southglenn Mall is being rebuilt as the outdoor Streets at Southglenn. As housing prices rose in Park Hill and Five Points, its Montbello neighborhood -- cut off from the rest of the city by I-70 -- became known as Denver's primary example of a "suburban ghetto," and is now being struck by a crippling wave of home foreclosures and vacancies.

Perl-Mack dissolved in 1983, but with Jordan Perlmutter & Co., Perlmutter continues to develop projects in the north metro area. (His second cousin, Ed Perlmutter, just won the 7th Congressional District house seat, which includes Northglenn.) Last year, Perlmutter opened Larkridge, a 240-acre power center on the far tip of Thornton. Featuring a Sears Grand, a Circuit City, a Dick's Sporting Goods and more, Larkridge is projected to become the biggest shopping center in Colorado -- and the centerpiece for a new boom in housing to the north.

As Bill Sullivan slowly drives his hatchback through the winding streets of Northglenn, he gazes intently at the houses, like a scientist alert for any variations in his experiment. He points out the nicely kept lawns and such small details as flowerpots and new fences.

"This guy, he's involved with everything in the city," Sullivan says, indicating a two-story house with lattices attached to the sides. "And next door, he says, he has a house with six families living there." It's the middle of the day, and four trucks are parked on the street in front of the house.

In Denver, over-occupancy complaints are common. But Northglenn has only begun getting such reports.

Sullivan laughs. "This whole area is going brown and more working-class," he says. "And you don't hear people talking about that. But you have to recognize it. The current population is going to be selling their house -- or being unsuccessful at selling their house -- and renting it out for $800 to $1,000 a month."

Often, you can spot the rentals that are the dots on Sullivan's map: The bushes are overgrown, and weeds poke up through cracks in the driveway.

Sullivan pulls up to the house at 1710 Leroy Drive, which was being used as an office for the parks and rec department. The city deeded it to the Northglenn Neighborhood Development Corporation on the condition that the NNDC tear down the aluminum sheds in back and rehab the property. Sullivan's group is going to put $275,000 into the house and create a first-floor master suite, a dining room, a great room, an attached two-car garage and a wraparound porch.

"It's a 20,000-square-foot lot," he says with amazement. And it abuts green space.

For a city to encourage homeowners to stay put and update their properties is a low-cost way to test the theory that an inner-ring suburb can age gracefully. But it's a gamble. As he walks back to the car, Sullivan acknowledges that the NNDC will probably lose some money on the first houses redeveloped: "The people around here, they're scratching their head saying, ŒYou're going to put how much money into that house? Are you crazy?'"

But as Sullivan drives past another house with a cracked driveway, he argues that the city has to find a way to turn its momentum toward renewal rather than decline. "We've got to try to change that mentality," he says. "And we've got to get people thinking about how the city is going to change and how they're going to adapt."