Two North Dakota Cities, #1 and #2, Lowest Unemployment In The United States

From Midland, Texas, comes this news: Lowest unemployment rates in the nation with two cities in North Dakota in #1 and #2 spots.

Bismarck, N.D. 2.3
Fargo, N.D. 2.6
Ames, Iowa 2.7
Iowa City, Iowa 2.8
Lincoln, Neb. 2.9
Logan, Utah 2.9
Sioux Falls, S.D. 2.9 -- I always find this interesting
Midland, TX 2.9 -- the third oil play (after the Bakken and the Eagle Ford)

It's easy to think that the unemployment rate in Bismack/Fargo is due to the Bakken, but obviously the Bakken does not explain the Iowa, South Dakota, or Nebraska cities. Obviously there is something else at work here.  I have a hunch that would connect three dots but I've learned that everyone has an opinion on these sorts of things, so not much use in more idle chatter.