The bonds of a county that are authorized and issued for construction or improvement of public highways may be issued by complying with this article. The board of supervisors may, and on the petition of fifteen per cent of the qualified electors of the county, the board of supervisors shall, order an election by the real property taxpayers who are qualified electors of the county to determine whether the indebtedness shall be authorized.
A.R.S. § 28-6741