Iowa Code § 468.522: Change of date and time.

The date on which the annual election shall be held and the polling hours may be changed by the choice of a majority of electors of the district expressed by ballot at any annual election, and the return of the vote shall be certified in the same manner as the returns for election of trustees. The polling hours may vary from the requirements of section 468.516, but the polls shall be open for at least three consecutive hours between the hours of 8:00 a.m. and 5:00 p.m. on the election day.