Let’s define an elastic state as one that is relatively sensitive or responsive to changes in political conditions, such as a change in the national economic mood. (This is in the same way that, in economics, an elastic good is one for which demand is highly sensitive to changes in prices.)
For instance, if there are a series of strong jobs reports this summer, and President Obama’s standing improves by five percentage points nationwide, we’d expect his standing to improve by more than 5 points in an elastic state. This works both ways: if we went into another recession and Mr. Obama suffered a five-point decline in his popularity, he’d experience a larger decline in an elastic state.
An inelastic state, by contrast, is one which is relatively insensitive to these changes. In an inelastic state, a five-percentage-point change in the national environment might only affect Mr. Obama’s numbers by three percentage points instead.
Elastic states are those which have a lot of swing voters — that is, voters who could plausibly vote for either party’s candidate. A swing voter is very likely to be an independent voter, since registered Republicans and registered Democrats vote with their party at least 90 percent of the time in most presidential elections. The swing voter is also likely to be devoid of other characteristics that are very strong predictors of voting behavior. For instance, he is unlikely to be African-American, which very strongly predicts Democratic voting. And she is unlikely to be a Southern evangelical, which very strongly predicts Republican voting, at least recently.
The classic example of an elastic state is New Hampshire. It has a very high percentage of independents, and those voters are also independent-minded in practice. Almost all of New Hampshire’s voters are white, but very few of them are evangelicals, characteristics that roughly balance out (Mr. Obama won about 55 percent of the nonevangelical white vote in 2008).
A good example of an inelastic state is North Carolina. It has quite a few African-American voters, who are almost sure to vote for Mr. Obama. But it also has plenty of rural white Southerners, many of them evangelical conservatives, who almost certainly won’t. To a lesser extent, it also has some highly educated and very liberal white voters in the Research Triangle, who are also quite likely to be Obama voters. That doesn’t leave very many voters left over. North Carolina is a swing state (or at least it was in 2008), because the coalition of Democratic base voters was quite close in size to the coalition of Republican base voters. But it wasn’t a state with a lot of persuadable voters: it’s the kind of place where elections mostly boil down to turnout, and Mr. Obama — with his considerably stronger ground game — was able to edge out a win there in 2008. ...
In theory, the more elastic the better. You'd rather live in a state where citizens will, say, turn against a corrupt politician because he's corrupt rather than hunker down and say he's an SOB but he's our SOB. (Cue Lee Kwan Yew.)
Then Silver estimates elasticity by state, using a complex methodology that I'll take his word for:
On the other hand, Rhode Island is pretty notoriously crooked at the local level. Interestingly, it's the only majority Catholic state in the country.
It would be interesting to try to apply this type of analysis to state and local politics. Washington D.C., which re-elected Marion Barry mayor after he got out of jail, would still be pretty SOB-loyal even compared to other cities.
What about for groups? Which voting demographics are most elastic?