Iowa Code § 331.661: Multicounty office.

1. Two or more county boards of supervisors may adopt resolutions proposing to share the services of a county sheriff. The resolutions shall also propose that the question of establishing the office of multicounty sheriff be submitted to the electorate of the counties proposing to share the services of a county sheriff. The proposal is adopted in those counties where a majority of the electors voting approves the proposal.

2. The county sheriff shall be elected by a majority of the votes cast for the office of county sheriff in all of the counties which the county sheriff will serve. The election shall be conducted in accordance with section 47.2, subsection 2.

3. The office of multicounty sheriff is created effective on January 1 of the year following the next general election at which the county sheriff is elected as provided by this section and section 39.17.