Ohio Rev. Code Ann. § 5707.01

The board of county commissioners of any county at their June session, annually, may levy a tax not exceeding three mills on each dollar valuation of taxable property within the county, for county purposes other than for roads, bridges, county buildings, sites therefor, and the purchase of lands for infirmary purposes. For the purpose of building county buildings, purchasing sites therefor, and purchasing lands for infirmary purposes, the board may levy a tax not exceeding two mills on such valuation.