The question of what to call citizens of Utah is a long and thorny one; currently the US Government Printing Office uses "Utahn." [0]

Apparently this was a big 'issue' in the 80's, when the US government usage was "Utahan" or "Utahian," while the local usage was "Utahn." Webster's currently lists "Utahan" as the correct usage, as far as I can tell (their website is trash - searching for "Utahan" and "Utahn" just redirects to the "Utah" entry.

[0] https://www.govinfo.gov/content/pkg/GPO-STYLEMANUAL-2016/pdf...