Dispelling the long-held lament that Pittsburgh’s population is declining, Forbes included Pittsburgh (Allegheny County, more specifically) in a list of regions on the rise in its March 12 issue. While many recent rankings spotlighted Pittsburgh’s livability – due in part to its economic and quality-of-life transformation – Forbes’  inclusion of Pittsburgh as a “Comeback City” was based primarily on a single, telling data point.

Citing IRS figures, Forbes points out that Allegheny County completely reversed population decline between 2005 and 2009. In 2005 Allegheny County was down nearly 10,000 taxpayers, yet by 2009 more taxpayers move into than out of the county. This remarkable reversal has been a long time coming for the region that struggled for decades with out-migration and overall population decline.

In understanding this upward population growth trend, it is worthwhile to note a shift over the past decade in regional population shrinkage. While out-migration (people leaving Pittsburgh to find jobs in other regions) was a leading factor throughout the ‘80s and ‘90s, that trend slowed during the first decade of the 21st century, while natural decline (deaths outnumbering births) continued. Yet both of these types of shrinkage – according to the IRS and U.S. Census Bureau – slowed dramatically by the end of the decade, setting the stage for the net-population gains now on the horizon.

As “natural shrinkage” slows, the region will, in turn, get younger. This point is most clearly indicated by the fact that between 2000 and 2010, the city of Pittsburgh saw its median age decline from 35.5 to 33.2. Couple this with Pittsburgh’s hosting the international One Young World Summit this fall, and you’ll see – as the Pittsburgh Post-Gazette noted – that the face of Pittsburgh is growing younger.

Another misperception buster:  “brain drain” is no more in Pittsburgh. Between 2000 and 2010 college educated segments of the region’s population grew, with population loss concentrated among the less educated. The Wall Street Journal took note of this trend when citing Pittsburgh as a Top 10 Metro Area for “Brain Gain.” You can read more on that here.

And to read more on the region’s changing demographics, click here for a report (with graphs!) recently published by the Pittsburgh Regional Alliance.