Neb. Rev. Stat. §§ 3-603
For the purpose of acquiring and improving such aviation field, such county may, in lieu of issuing and selling bonds, levy an annual tax of not to exceed seven cents on each one hundred dollars of taxable value of all the taxable property within such county subject to section 77-3443. The tax shall not be levied or collected until the proposition of levying the same has first been submitted to the legal electors of such county at a general or special election held therein and received a majority of the votes cast upon the question of levying such tax. Such levy shall be authorized for a term not exceeding ten years, and the proposition submitted to the electors shall specify the number of years for which it is proposed to levy such tax. If funds for such purposes are raised by the levy of tax, no part of the funds so accruing shall be used for any other purpose.
Neb. Rev. Stat. §§ 3-603