Ohio - Criteria: A (event)
| Medina Farmers Exchange Co. |
| Medina Masonic Temple and Medina Theater |
| Meeker, Forrest, House and Farm |
| Meigs County Fairgrounds, Grandstand and Racetrack |
| Mellett-Canton Daily News Building |
| Melville-Milne, William Gordon, House |
| Memorial Hall |
| Mendon Town Hall |
| Mentor Village School |
| Methodist Church, Old |
| Methodist Episcopal Church |
| Metropolitan Block |
| Miami And Erie Canal, Deep Cut |
| Miami-Erie Canal Site Historic District |
| Michaels Farm |
| Middleport Public Library |
| Milan Historic District |
| Miles Park Historic District |
| Miller-Bissell Farmstead |
| Miller Farm |
| Miller, Frederick A., House-Broad Gables |
| Mill Office and Post Office |
| Mill Worker House No. 1 |
| Mill Worker House No. 3 |
| Mill Worker House No. 4 |
| Mill Worker House No. 5 |
| Miner's Supply Store |
| MISSISSIPPI III |
| Monroe Bank |
| Monroe County Courthouse |
| Monroe Township Hall-Opera House |
| Moore, Edward W. and Louise C., Estate |
| Moore, Philip, Stone House |
| Moreland Theater Building |
| Morgan, John H., Surrender Site |
| Morgan Township House |
| Morris, C. E., House |
| Morristown Historic District |
| Mound City Group National Monument |
| Mount Adams Public School |
| Mount Airy Forest |
| Mount Auburn Historic District |
| Mount Orab Station |
| Mount Pleasant Historic District |
| Mount Union College District |
| Mount Victory Historic District |
| Mount Zion Baptist Church |
| Mount Zion Presbyterian Church |
| Mt. Olive Road Covered Bridge |
| Mueller Brewery |
| Mueller Electric Company Building |
| Municipal Building |
| Municipal Light Plant |
| Murray Hill School |
| Muskingum River Navigation Historic District |
| Myers Block-Home Company Building |
| Myers Daily Market |
| Nafzger-Miller House |
| NASA Lewis Research Center-Development Engineering Building & Annex |
| National Home, Daughters of America |
| National Road |
| Neal Terrace |
| Neff, Conrad, House |
| Nela Park |
| Newark High School |
| New Baltimore Inn |
| Newberry Township School |
| New England Building |
| New Hayden Building |
| New Market Township Community House |
| New Straitsville School |
| Newton Falls United Service Organization (USO) Center |
| New York Central Freight House |
| No. 5 Fire Station |
| Noble County Jail and Sheriff's Office |
| Norfolk And Western Railroad Depot |
| North Bass School |
| North Columbus Commercial Historic District |
| Northfield Town Hall |
| North Main-North Detroit Street Historic District |
| North Market Historic District |
| North Olmsted Town Hall |
| North Presbyterian Church |
| Norwalk Memorial Hospital |
| Nurre-Royston House |
| Oak Hill Cottage |
| Oak Hill Welsh Congregational Church |
| Oakwood Cemetery Chapel |
| Oberlin College |
| Oberlin Gas Lighting Company Gasholder House |
| Oberlin Lake Shore And Michigan Southern Station |
| Observatory Historic District |
| Odd Fellows' Home for Orphans, Indigent and Aged |
| Odd Fellows Temple |
| Oesterlein Machine Company-Fashion Frocks, Inc. Complex |
| Ohio and Erie Canal |
| Ohio Bell Henderson-Endicott Exchange Building |
| Ohio City Preservation District |
| Ohio Farm Bureau Federation Offices |
| Ohio Finance Building |
Data from United States Park Service and Wikidata
