Calling Sioux City, Iowa an armpit is bound to be controversial as some will think it too harsh and others not harsh enough. Truth be told, I've never set foot in the city proper. My conclusion is based solely on the fact that the only interstate running south out of South Dakota, I-29, runs through it and it has been under construction since at least 2009. Worse, there is no end in sight as I discovered to my chagrin yesterday (SUNDAY, 27 Sept. 2015) while driving back to Sioux Falls from Cincinnati. (Hey, it is WAY better than flying especially when there are no construction delays, which was the case until I hit the armpit.)
It would have been faster, and I suspect cheaper, if they had built a 229-like belt around Sioux City, de novo, and then simply closed 29 down for how ever long it took to complete whatever the heck it is they are doing. But the real stench (whether you think of an armpit or another body part to describe the place) comes from the speed trap cameras. Instead of allowing some private company to reap the benefit of the cameras, like some French Ancien Regime tax farm, the proceeds ought to go to reimburse the poor souls trapped in the hairy armpit by needless Sunday construction delays.
ADDENDUM 19 March 2017: Recently drove thru this "armpit" and it is STILL under construction. As our beloved president would say, "pathetic."
UPDATE: October 2017 drove through again on the way to STL. The armpit is STILL a mess. It is going on a decade now.