Pittsburgh is the second largest city in the state of Pennsylvania and has the largest metropolitan combined statistical area in the Ohio Valley and Appalachia. Known as the Steel City for its 300 steel-based businesses and the City of Bridges for a world-record 446 bridges, Pittsburgh has earned the title of the "most livable city" by Forbes and The Economist and a reputation for its environmental design.

This may seem at odds until you consider that Pittsburgh's city limits are virtually unchanged from a century ago, while other cities like Houston, Phoenix, and San Diego keep annexing their suburbs and gaining land area. The last time Pittsburgh expanded its city boundaries was in 1907.

If Pittsburgh expanded its city limits to around the same area as any other city in the top 10, its population would grow from around 300,000 to over one million, and it would become the 9th most populous city in the US, a massive jump from 56.

That means that while Pittsburgh seems to be shrinking on paper, it's growing quite massive as more people move to the suburbs. The city population density is now at 5,540 people per square mile (2,140/square kilometer). The urban area is home to 1.733 million, the metro area has 2.36 million, and the Combined Statistical Area (CSA) has an estimated 2.62 million in 2013.

Pittsburgh Population and Diversity

According to the 2010 Census, Pittsburgh experienced an 8.6% drop in population. On paper, the city has been shrinking since the 1960s, and hasn't seen growth above 1% since 1930, although this is due, in part, to its unchanging city limits.

The largest white ancestry groups in Pittsburgh include German (19.7%), Irish (15.8%), Italian (11.8%), Polish (8.4%) and English (4.6). The metropolitan area as a whole is 22% German, 21% Irish and 12% Italian. This means Pittsburgh has one of the largest Italian communities in the United States. It also has the largest Croatian community at over 200,000 and the 5th largest Ukrainian population in the US.

Pittsburgh Population Growth

While known for its steel-dominant industries, Pittsburgh has started to branch out and transition from manufacturing dependence to a more diverse economy. This could be the opportunity it needs to get away from the slump its population has seen over the past 60 years. After many decades, it seems Pittsburgh may be the latest boomtown in the United States.

In 2012, Forbes called Pittsburgh the "comeback city," as it's actually started to reverse population decline. Forbes pointed to the fact that Allegheny County had reversed its decline between 2005, when it was down 1,000 taxpayers according to the IRS, to 2009, when more had moved into the country than out.

This means both out-migration and natural decline could be at an end, and it means Pittsburgh may soon see a population that gets younger. From 2000 to 2010, its median age dropped from 35.5 to 33.2.

It's still too early to predict Pittsburgh's population at the next census in 2020, but there has been a drop of approximately 3,000 people as of 2017.