2012 exit poll for Senate:
Interesting there's not much difference between the age groups in MT.
Presumably because older cohorts from MT are of a more Democratic lean historically (at least among native Montanans), and younger people are disproportionately either college students (transplants or otherwise) and/or yuppies looking to be edgy in their living arrangements.
On the surface, MT strikes me as one of these states that doesn't have a large native young population, given its recent growth has likely been fueled by middle-aged outsiders (who, despite their lean toward the GOP, would still be more Democratic than native-born middle-aged Montanans).
I could totally be wrong about all of this