Ohio Revised Code 4511.21 Speed limits.

(A) No person shall operate a motor vehicle, trackless trolley, or streetcar at a speed greater or less than is reasonable or proper, having due regard to the traffic, surface, and width of the street or highway and any other conditions, and no person shall drive any motor vehicle, trackless trolley, or streetcar in and upon any street or highway at a greater speed than will permit the person to bring it to a stop within the assured clear distance ahead.

(B) It is prima-facie lawful, in the absence of a lower limit declared pursuant to this section by the director of transportation or local authorities, for the operator of a motor vehicle, trackless trolley, or streetcar to operate the same at a speed not exceeding the following:

(1)(a) Twenty miles per hour in school zones during school recess and while children are going to or leaving school during the opening or closing hours, and when twenty miles per hour school speed limit signs are erected; except that, on controlled-access highways and expressways, if the right-of-way line fence has been erected without pedestrian opening, the speed shall be governed by division (B)(4) of this section and on freeways, if the right-of-way line fence has been erected without pedestrian opening, the speed shall be governed by divisions (B)(9) and (10) of this section. The end of every school zone may be marked by a sign indicating the end of the zone. Nothing in this section or in the manual and specifications for a uniform system of traffic control devices shall be construed to require school zones to be indicated by signs equipped with flashing or other lights, or giving other special notice of the hours in which the school zone speed limit is in effect.