Ohio Rev. Code § 5557.09
Whenever the boundary line of a municipal corporation is located within or along the side lines of a street, avenue, road, or other public highway and adjoins unincorporated territory, such municipal corporation may enter into an agreement with the board of county commissioners for the improvement of such street, avenue, road, or other public highway in such manner as the legislative authority of the municipal corporation and the board of county commissioners may determine. The agreement may provide for any of the improvements specified in section 727.01 of the Revised Code, and the cost and expense thereof may be assessed upon the property specially benefited. By the agreement, the cost of the entire improvement shall be apportioned between the municipal corporation and the board of county commissioners as the legislative authority and the board may agree and the legislative authority of the municipal corporation and the board of county commissioners shall each determine whether or not any portion of the cost to be paid by it shall be specially assessed or paid from other funds of the municipal corporation or county available for such purpose. Such agreement shall designate either the municipal corporation or the board of county commissioners to take exclusive charge of the details of the improvement, including advertising for bids and awarding the contract. Such contract may be entered into by such municipal corporation or board when the necessary funds have been provided therfor, and when the amount to be paid by the other has been paid to the municipal corporation or board authorized to supervise such construction. Assessments made by a municipal corporation under such agreement shall be made in the manner and subject to the limitations provided in sections 727.01 to 727.49 of the Revised Code. Assessments made by a board of county commissioners under such agreement shall be made in the manner and subject to the limitations provided in sections 5555.06 and 5555.07 of the Revised Code.
Bonds may be issued and sold in anticipation of the collection of the assessments by either the municipal corporation or the board levying the assessments, and bonds may likewise be issued and sold by either the municipal corporation or the board for the purpose of paying its share of such improvement under the conditions and limitations, and in the manner provided by Chapter 133. of the Revised Code.
"Improvement" as used in this section includes constructing, reconstructing, grading, draining, curbing, paving, repaving, straightening, widening, and repairing the street, avenue, road, or other public highway and also includes the constructing and reconstructing of sidewalks, drainage ditches, storm sewers, bridges, and culverts.
R.C. §5557.09