Which states will shift Republican over the next few decades?

[Nichlemn]

What about Washington, Oregon and Michigan?

WA and OR are trending dem and will keep trending dem. Hard to tell for Michigan, but I don't see it turning rep.

Isn't Michigan a fair bit like Pennsylvania demographically? Why would PA trend Democratic while Michigan doesn't? (Or are you saying that it might trend Republican, but not enough to be more Republican than average?) Also, around half of all states in most cases must trend Republican. What are the states that are more likely to trend Republican than Michigan?

An annoying thing I have seen was Democrats after 2008 claiming that nearly every state was "blueing" and Republicans after 2010 claiming than nearly every state was "reddening". But in terms of trends, that obviously can't be the case.

[Nichlemn]

Michigan is far more solid than Pennsylvania. I can't see it shifting rep before many time.

"Far more solid"? Arguably true for 2008, but not really in any other elections. MI was only slightly more Democratic than PA from 1996-2004, however, it was less Democratic from 1984-1992. Another thing that can be inferred from state trends is that PVIs can change quite quickly.

Also, it's unclear whether you mean "become a Republican-leaning state" or "trend Republican".

[Nichlemn]

Why is everyone thinking PA is trending GOP?  Western PA, sure.  It's old, white, and similar to West Virginia, but it's losing population.  The fastest growing counties are rapidly trending Democratic.  The Pocono region is another mixed bag.  The eastern Poconos are trending Dem due to NYC influences, but the western Poconos/Lackawanna Valley will likely trend GOP.  Look at Lancaster County.  Once nearly impossible for a Dem to win, Obama cam pretty close and people from Philly and Baltimore are moving in fast.

Overall, I'd say PA is stable, if anything trending narrowly Dem with all said and done. 2010 was a blip on the radar due to fiscal issues, but Corbett is wildly unpopular in the Southeast.

It has slower Hispanic growth than average (well, I'm pretty sure it does), so it should be able to trend Republican (in the Atlas sense) by standing still.

[Nichlemn]

Why is everyone thinking PA is trending GOP?  Western PA, sure.  It's old, white, and similar to West Virginia, but it's losing population.  The fastest growing counties are rapidly trending Democratic.  The Pocono region is another mixed bag.  The eastern Poconos are trending Dem due to NYC influences, but the western Poconos/Lackawanna Valley will likely trend GOP.  Look at Lancaster County.  Once nearly impossible for a Dem to win, Obama cam pretty close and people from Philly and Baltimore are moving in fast.

Overall, I'd say PA is stable, if anything trending narrowly Dem with all said and done. 2010 was a blip on the radar due to fiscal issues, but Corbett is wildly unpopular in the Southeast.

It has slower Hispanic growth than average (well, I'm pretty sure it does), so it should be able to trend Republican (in the Atlas sense) by standing still.

Also don't assume Hispanic growth=Dem trend.  Most Hispanics I know are quite socially conservative and religious.  And with the old white perception PA has, remember they're dying off and not many kids to replace them.  Sure western PA will continue to trend conservative and Mark Critz's district will be washed into GOP oblivion, but still watch eastern PA which is more populated, growing, and trending Dem save the classic blue collar ethnic Catholic areas such as Scranton/Wilkes Barre/Hazleton plus Northeast/South Philly and even those areas are a push in terms of trends.

Hispanics may become less Democratic, but it'll be a long time (if ever) that Hispanic growth doesn't result in a Dem swing (resulting in Rep trends by default in other states).

The main reason I say this is that I see many plausible-seeming arguments that just about every state is trending Democratic. Apparently the West is all trending Democratic, the Northeast is static or trending Democratic, much of the South is static or trending Democratic. Mathematically, about half of all states should be trending Republican, so where could they all be? Pennsylvania seems like an obvious candidate.

[Nichlemn]

Over the long term, yes, equal amounts of states will trend both ways as the parties change to stay competitive.  The long term is also hardest to predict.

In the short and middle term, I would say more states are trending Democrat simply because of hispanic/ urban growth and the youth vote. 

I'm referring to the Atlas definition of trend, which is "swing relative to the national swing". If all states swing Dem, but some swing Dem less than others, than those states have trended Republican.

[Nichlemn]

The Simpsons says it well:

Disco Stu: "Did you know that disco record sales were up 400% for the year ending 1976? If these trends continues... AAY!"

[Nichlemn]

Also, according to Democratic bulls here, almost every demographic change is good for Democrats. So long as Illinois has less of that than average, it will trend (Atlas definition) Republican.