Ohio Rev. Code § 703.06
When the result of any federal census or an enumeration as provided in sections 703.02 to 703.05, inclusive, of the Revised Code, is officially made known to the secretary of state, he forthwith shall issue a proclamation, stating the names of all municipal corporations having a population of five thousand or more, and the names of all municipal corporations having a population of less than five thousand, together with the population of all such municipal corporations. A copy of the proclamation shall forthwith be sent to the mayor of each such municipal corporation, which copy shall forthwith be transmitted to the legislative authority of such municipal corporation, read therein, and made a part of the records thereof. Thirty days after the issuance of such proclamation each municipal corporation shall be a city or village as the case may be.
R.C. §703.06