at what point should dems hit the panic button in PA?

[pa2011]

If you look on a map of PA with recent election results, appears Dems are fine in PA for awhile. Seems actual city of Pittsburgh is a pretty strong firewall for Democrats in increasingly conservative Southwest PA.

So Allegheny County -- which Pittsburgh is in -- looks pretty set at producing just under 100,000 vote margin for Dems in presidential election years, even though Pittsburgh suburbs are pretty red now. It's been just about 100,000 vote D margin in 2000, 2004, 2008 and 2012.  

That margin basically cancels out all the Republican-trending counties that surround Allegheny.

Likewise, seems Dem have a firewall with the smaller city of Erie in Northwest PA of about 20,000 vote advantage, (Bush kept it to 10,000 in 2004 but Obama got 25,000 margin in 2008). Regardless, that margin basically cancels out the Republican vote in the rest of Northwest PA.

That leaves Philadelphia to cancel out all the two dozen or so lightly populated hard R counties in central Pennsylvania. Usually pretty easy for Philly to do plus some in presidential election years. And think Philly like many cities has has finally stopped losing population, so probably pretty stable for now in that regard.

That leaves  Philadelphia suburbs and Northeast Pa. Imagine trends in Philadelphia burbs will continue to favor D's, though agree a candidate like Christie could run strong. Northeast PA could keep trending away from Democrats to some extent, but some of that may be balanced out by a growing Hispanic population in cities such as Reading and Scranton. Plus, I think some New Yorkers are choosing to retire in the Pocono Mountains, so that should also help Democrats in the long-term.

[pa2011]

But if  there ever were a big drop off in African-American interest/turnout, obviously my above scenerio goes out the window.  Allegheny County becomes a pure toss up, and Philly would be unable to counteract the Republican vote in central Pa.