According to the Census Bureau data released Thursday Philadelphia County had the greatest natural population increase at 19,940.
Lancaster and Chester counties were a distant second and third. Westmoreland County in western Pennsylvania had the greatest natural decrease at minus 2,503, followed by Luzerne County and Allegheny County.
But those who see more people in Pittsburgh aren't imagining them. Allegheny County gained 5,990 people overall because of immigration. Statewide there were 37,311 more births than deaths from 2010 to 2012, and the total population increased by 61,157 to 12,763,536.
The shows that Blair County’s overall population increased by less than 100 people.