Where any township or county road is located as by law provided, upon the dividing line between two townships or two counties, it shall be the duty of the township boards of highway commissioners, or the boards of county commissioners of the townships or counties between which such road may be located to maintain, repair or improve said road between the two townships or counties, and it shall be the duty of the township boards or boards of county commissioners to supervise and provide for the maintenance, repair and improving of such roads: Provided, That in case such road or roads do not, in the judgment of the two county boards having jurisdiction, have sufficient travel to make their upkeep sufficiently necessary to the public, the county commissioners of the two counties may, when both boards concur, cause such road or roads to be vacated according to law and closed under the same conditions as provided by statute for the closing of a road within the county: And provided further, That in case a road is located on the dividing line of two counties and is a county road, then it shall be the duty of the adjoining counties to repair, maintain and improve said road as above provided, but if the road be a township road, then it shall be the duty of the adjoining townships to repair, maintain and improve such road.