Ohio Rev. Code § 5589.33
Except as provided in this section and in section 5515.04 of the Revised Code, no person shall place within the limits of the right-of-way or affix any sign, poster, or advertisement to any tree or utility pole within the right-of-way of any public highway outside of municipal corporations. No person, organization, corporation, or group shall place within the limits of the right-of-way any object as determined by the department of transportation to obscure sight distance.
Nothing in this section shall be construed to prohibit the erection and maintaining of notices of the existence and location of public utility facilities under or upon the highway and warnings against disturbing such facilities, or of notices that emergency or other public telephones are available for users of the highway at specified locations upon or near the highway.
R.C. §5589.33