Ohio Rev. Code § 4504.03
The county engineer of any county levying a county motor vehicle license tax shall within ninety days after the effective date of the resolution levying the tax prepare and file with the board of county commissioners a comprehensive map of the roadways of the county, designating separately thereon interstate highways, state highways, intercounty roads, county and township roads forming a part of the system of county highways established pursuant to Chapter 5541. of the Revised Code, and those streets located within municipal corporations in the county not included in any of the foregoing which are determined by the county engineer to be necessary or conducive to the orderly and efficient flow of traffic within and through the county. Such municipal streets may be designated by the county engineer as primary and secondary based upon their relative importance to the orderly and efficient flow of traffic within and through the county.
The county engineer may consult with the officers of the municipal corporations within the county in charge of the construction, improvement, and maintenance of municipal streets and he may designate on the map prepared pursuant to this section any proposed streets which he determines will be necessary or conducive to the orderly and efficient flow of traffic within and through the county.
Upon adoption by the board of county commissioners of such map, with such modifications as they deem necessary, a copy of such map shall be made a part of its records and copies thereof shall be filed in the office of the county engineer and with the state director of transportation and the clerk of the legislative authority of each municipal corporation in the county. Such map may be revised from time to time by the county engineer upon approval of the board of county commissioners, and copies of the revised map shall be filed in the same manner as the original map.
R.C. §4504.03