Perhaps because in North Dakota, the state legislature meets only every other year and for a maximum of 60 days (usually somewhat more but not much)and most if not all of the legislators return to farms, ranches, or other careers when the session is over.
Any who forget where they came from get voted out of office. Unfortunately, that rule does not apply as much to those who get promoted to Washington and make frequent cameo appearances and/or bring home pork.
Also might have to do with Chicago being so corrupt...