As far as states go, New Jersey, Illinois and Maryland are up there; although, each has some redeeming values.
For real armpits, you need to be more specific. Here's my rogue's gallery of USA crapholes...
MAJOR LEAGUE DIVISION
Washington, DC
Detroit, MI
Buffalo, NY
San Francisco, CA (probably the worst; a human stockyards)
MINOR LEAGUE DIVISION
Beaumont/Port Arthur/Orange, TX
Waterloo, IA
Gallup, NM
Gary, IN
New Haven, CT
Camden, NJ
While I am in agreement that the City of Buffalo is a hole, much of the surrounding suburbs and points South and East are much easier on the eyes. I will, however, nominate the region as having some of the dopiest people in the U.S. The Dems have literally destroyed this area with their policies and corrupt politics, yet the dimwits living in the Western NY region still mindlessly vote many of these same people into office over and over.