For one thing, Pierre is tiny. Also, Both Pierre and Bismarck are in remote areas west of the more populated (and liberal) farming, eastern edges of the Dakotas. Bismarck is similar in size and politics to Rapid City, and both are pretty isolated. Here in South Dakota, once you get west of the James River to the western two-thirds of the state, it becomes more wild, western, ranching country.
You mean relatively? The eastern portions of the Dakotas vote republican too.
Yes, I'm meant more liberal than the the more western parts of the Dakotas.