How is Phoenix going to get rid of that oversupply of empty houses if people are picking up and moving out of the Valley? [Hat tip MR!]

For the first time in modern history, Phoenix’s population could be shrinking.

It’s an idea that would have been unimaginable just a few years ago, when Phoenix was surging up the list of the nation’s most populous cities. Now, a variety of indicators suggest that fewer people are living here than a year ago.

No one knows for sure exactly how many people have moved in or out. But with the 2010 census about to get under way, some indicators suggest Phoenix’s population may be smaller than the projected 1,636,170 people.

City records show declining trends in several key areas. Among them:

• Foreclosure numbers have skyrocketed, meaning fewer city homes are occupied.

• Water hookups are down, suggesting the same.

• Some aspects of trash collection have ebbed because fewer people are buying things that produce waste.

• Crime has declined across the city while police are getting fewer calls for services, a possible indicator of fewer people.

• Sales-tax revenues are likely to drop for the second year in a row, with this year’s collections off almost 8 percent from last year.

A large portion of the Phoenix population are fairly recent arrivals, many of whom moved to the Valley for jobs.  While many grow to love the climate and the lifestyle and will try and stay, often people move on to where the jobs are.

This is one more reason to believe that the housing market in Phoenix will be depressed for some time to come.