Utah Code § 17-3-4
Whenever a new county shall have been created under the provisions of this chapter, the county legislative body of the county from which territory has been taken to create such new county shall provide for an election to select a county seat therefor and to elect officers for the new county; provided, that whenever the petitions provided for in this chapter shall be presented to any county legislative body during a year when no general election is held they shall call a special election to select a county seat and county officers for such new county, such election to be held on the first Tuesday after the first Monday of November following and to be conducted under the laws providing for general elections. The city or town receiving the largest number of votes therefor shall be the county seat of the new county.
Utah Code § 17-3-4