Ohio Rev. Code Ann. § 5555.31

When the proposed improvement is wholly within one county but within less than the legal assessment distance of the county line, and a petition is filed asking for such improvement, signed by fifty-one per cent of the persons to be specially assessed therefor, such improvement shall be regarded as joint county improvement, and shall be made in accordance with sections 5555.21 to 5555.30, inclusive, of the Revised Code.