Utah by far... Idaho does have a Democratic legacy with Frank Church, and I believe has elected Democratic Governors in recent memory.
Utah doesn't elect Democrats, and I don't know the last time a Democrat was elected to office there.
I suppose you are just counting the statewide level, because Jim Matheson is now a four-term Congressman.
I had no clue who Jim Matheson even was.
Democratic Congressman from UT-02. Blue Dog, but Democrat nonetheless.
'Kay. I still think one guy doesn't make up for say... Five guys.