Allentown and Reading showed major growth since the 2000 Census, while Pennsylvania's other two major cities - Pittsburgh and Erie - both lost population, the data show.
Philadelphia's population of more than 1.5 million rose by only 0.6 percent - about 8,500 people - but Mayor Michael Nutter proclaimed the growth no small feat and "something that no mayor has been able to say since 1950."
"Philly really is on the way back," Nutter said. "This Census count is just the beginning."
Overall, the 2010 statistical portrait of Pennsylvania showed eastern and central counties with the biggest gains over the past decade. Western counties generally lost residents.
The number of Pennsylvania residents increased 3.4 percent, to just over 12.7 million. Still, the state will lose one of its 19 congressional seats because of the demographic changes.
The state's Hispanic population has increased nearly 83 percent, from about 395,000 to almost 720,000. The Asian population grew nearly 59 percent, to 349,000.
The city of Allentown grew by 10.7 percent to just over 118,000, while Reading increased by 8.5 percent to nearly 88,100.
But Pittsburgh, the state's second-largest city, lost 8.6 percent of its population, leaving about 305,000 residents; its home, Allegheny County, totaled about 1.2 million people, a 4.6 percent decrease.
The city of Erie lost 1.9 percent of its residents and now has about 102,000.
Chris Briem, a regional economist at the University of Pittsburgh, said while the Pittsburgh area shows a decline, the numbers may not reflect recent improvements.
"Ten years is a long time, and it doesn't always capture what's going on year over year," Briem said.
Pittsburgh has been touting itself as a hub for green jobs and technology companies, and has raised its profile by hosting the G-20 economic summit and being named "Most Livable City" in the U.S. by The Economist magazine in 2009.
It's not that people are necessarily leaving the region, Briem added, noting there are more deaths than births in western Pennsylvania because the population is more elderly.
The counties that lost the most population - between 5.1 percent and 14.9 percent - were all in the west: Beaver, Cambria, Cameron, Elk, Fayette and McKean.
And though some say gas drilling in the Marcellus Shale region may draw more people to rural Pennsylvania, Briem said so far the industry has attracted mostly itinerant workers who stay for a while but return home to other states.
"It remains to be seen whether there's going to be a demographic impact," Briem said.
Growth in south-central Pennsylvania ranged from zero to 19.9 percent, which Briem ascribed to increasing numbers of commuters to the Baltimore and Washington areas.
Tiny Forest County in the northwestern part of the state technically experienced the most growth - 56 percent - but officials there attribute it to a prison that opened years ago in Marienville.
The next two biggest increases, between 20 and 25 percent, were in Monroe and Pike counties on the New Jersey border.
Monroe County Chief Clerk Bob Gress credited the growth to highways linking the area to the Philadelphia and New York metropolitan regions, as well as great schools and recreational activities in the Pocono Mountains.
"It's a great place to raise your family," Gress said.
In Philadelphia, the mayor conceded the 0.6 percent growth is "not a whole, whole lot of people," but said it means the city is moving in the right direction. He attributed it in part to a heavily promoted Census participation campaign and Philadelphia's growing reputation for arts, culture, sustainability and safer streets.
"We are the hot place to be," Nutter said.
Philadelphia had 2 million people in 1950 but steadily lost population as its manufacturing facilities closed and residents moved to the suburbs.