The midwest can definitely get dark, but the "seeing" isn't as good as the oregon outback for a few reasons, 1) elevation, most of eastern oregon is above 1200m, steens mountain is almost 3000m. 2) climate, the midwest can be very humid and hazy, whereas the high desert is very arid and clear, 3) obscuration, eastern oregon is covered in mountain ranges with dry basins in between (hence "basin and range" name), and you only have to go over one range from any kind of town to have its light totally blocked.
Can you elaborate on why the elevation matters? I mean, a few thousand feet isn't going to make up the distance between the earth and the star providing the light. ;)
