What differentiates Montana and the Dakotas?

[freepcrusher]

Montana and both Dakotas seem willing to elect Democratic senators, and they have a PVI of R+10 or less. Compare that to many other deeply red interior West states, like Nebraska, Kansas, Idaho, Wyoming, etc. What separates the Dakotas and Montana from the other, more deeply red, interior West states?

remember that from 1977-2013, Nebraska had at least one dem senator (two from 79-87 89-97). What separates Montana from an Idaho or Wyoming is unions, especially in mining.