Ohio - Area of significance: Commerce
| Putman, Walter S., House |
| Pythian Castle |
| Quaker Oats Cereal Factory |
| Race Street Historic District |
| Rawlings-Brownell House |
| Rawson House |
| Raymond, Liberty G., Tavern and Barn |
| Realty Building |
| Record Rendezvous |
| Reeser, C. A., House |
| Reidy Bros. & Flanigan Building |
| Rentschler House |
| Reynolds, John R., House |
| Riddle Block |
| Riverview |
| Rohr, David, Mansion And Carriage House |
| Root and McBride-Bradley Building |
| Roscoe Village |
| Sail Loft |
| Salem Downtown Historic District |
| Sandusky Street Historic District |
| Santa Clara Business Historic District |
| Satterthwaite, John, House |
| """S"" Bridge II" |
| Schmick, Charles Nelson, House |
| Schmitt, Louis, House and Store |
| Schuffenecker, August Building |
| Schulte-United Building-G.C. Murphy’s Building |
| Sears, Roebuck and Company |
| Second Street Historic District |
| Secor Hotel |
| Secor, Joseph K., House |
| Seville Inn |
| Shaker Square |
| Shelby Center Historic District |
| Shield's Block |
| Short North Historic District |
| Sidney Walnut Avenue Historic District |
| Skywood Farms |
| Smart Building |
| Smucker, J.M., House |
| Snider, Dan F., Ford Dealership Building |
| Sorrick-Oster Store |
| South High Street Commercial Grouping |
| South Main Street Historic District |
| Southworth House |
| Spang, J., Baking Company |
| Springboro Historic District |
| Springfield Downtown Historic District |
| Stadium Square Historic District |
| Stagecoach Inn |
| Stambaugh Building |
| Standard Building, The |
| Stanley Block |
| State Theater |
| St. Clairsville Historic District |
| Steamboat Hotel |
| Stedman-Shafer Grocery Warehouse Building |
| St. Edward Hotel |
| Steubenville Commercial Historic District |
| Stoneman, Joseph, House |
| Strouss-Hirschberg Company |
| Stump, John, House And Mill |
| Stumpy Basin |
| Stuyvesant Motor Company Building |
| Succesful Sales |
| Sullivant, Lucas, Building |
| Sunday Creek Coal Company Mine No. 6 |
| Superior Avenue Historic District |
| Superior Avenue Viaduct |
| Swetland House |
| Tallmadge-Mithoff House |
| Tavener-Sears Tavern |
| Taylor, Colonel Joseph, House |
| Tecumseh Building |
| Templar-Farrell Motor Sales Building |
| Temple and Masonic Block Buildings |
| Templin-Bradley Company |
| The Broer-Freeman Building |
| Theresa Building |
| Third Avenue and North High Historic District |
| Tiedemann, Hannes, House |
| Times-Star Building |
| Tinkers Creek Aqueduct |
| Toledo Central Business Historic District |
| Toledo City Market |
| Toledo Harbor Light |
| Tosheff's Restaurant and Hotel |
| Town Center District |
| Travelers Hotel |
| Troy Public Square |
| Tuscarawas Avenue-Alexander Square Commercial Historic District |
| Tuttle House |
| Twelve Mile House |
| Underwriters Salvage Corps |
| Unger, George B., House |
| Union Terminal Group |
| Universal Terminal Company Dock and Warehouse |
| Upper Downtown Canton Historic District |
| Upson-Walton Company Building |
Data from United States Park Service and Wikidata
