PHOENIX - It's not the typical inspiration for a news story, but The Onion recently proclaimed (as a joke), that scientists had found the entire world would be covered with suburbs of Phoenix by the year 2050.

Of course it's not true, but anyone who's seen the massive construction projects in downtown Phoenix, as well as the ever-expanding borders of the Valley, can't help but wonder how much truth there is in the joke.

"The same kind of land speculation that took place in the outskirts of town, happened downtown before the recession," Tim Sprague, project principal for Portland on the Park said.

Portland on the Park is the next phase of a construction project that had to be put on hold when the housing market crashed. Now the 12- and 14-story condo towers are a few months from opening.

Sprague said developers saw the arrival of light rail as a harbinger of things to come.

"It was transformative," Sprague said. "We saw this land was becoming available, we said, 'let's do it.'"

Portland on the Park is one of a number of residential complexes that will drastically increase the downtown population.

Sprague said in the immediate area around his project, there are approximately 5,900 residents. In the next two years, he expects the projects that are already under construction to double that number.

The Phoenix metro area has no natural land breaks to the east, west or south. But Maricopa County officials said the Valley probably won't keep expanding until it collides with California or Mexico; it's too expensive to keep annexing land and providing services. Plus, county officials said, annexation is a public process where people can weigh in on losing their open spaces to development.

But Downtown Phoenix, Inc. Executive Director Dan Klocke said the demand to keep growing is there. And the new developments in downtown Phoenix are all above 90 percent capacity.

"There's a big enough market for both," Klocke said. "But there's a huge market now for people wanting to live in the central city and downtown."