| Tri State Heating Supply | Fort Wayne | IN |
| Tri State Refinery | Evansville | IN |
| Tri-State Refractories | Evansville | IN |
| Triton Central School | Fairland | IN |
| Troy Towel & Supply | Fort Wayne | IN |
| Truman Minor | Evansville | IN |
| Trunkline Gas | Kentland | IN |
| Turbo-Blower House | Gary | IN |
| Twin Branch Power | Mishawaka | IN |
| Twin City Insulation | South Bend | IN |
| Underwood Manufacturing | Wabash | IN |
| Union Carbide | Kokomo | IN |
| Union Carbide | Whiting | IN |
| Union Carbide | East Chicago | IN |
| Union Carbide | Speedway | IN |
| Union Carbide | Indianapolis | IN |
| Union Carbide | Gary | IN |
| Union Drawn Steel | Gary | IN |
| Union Electric Steel | Valparaiso | IN |
| Union Fraction | Anderson | IN |
| Union Hospital | Indianapolis | IN |
| Union Metal Products | Hammond | IN |
| Union Real Estate Building | Anderson | IN |
| Union Tank Car | East Chicago | IN |
| Union Tank Car | Whiting | IN |
| Union Traction | Anderson | IN |
| United Box Board | Wabash | IN |
| United Engineering & Foundry | Hammond | IN |
| United Hospital Laundry | Indianapolis | IN |
| United Methodist Church | Sellersburg | IN |
| United Paper Board | Wabash | IN |
| United Plumbing & Heating | Fort Wayne | IN |
| United Public Service | Rochester | IN |
| United Refrigerator | Richmond | IN |
| United States Gypsum | East Chicago | IN |
| United States Penitentiary | Terre Haute | IN |
| United States Railway Equipment | Washington | IN |
| United States Reduction | East Chicago | IN |
| United States Rubber | Fort Wayne | IN |
| United States Rubber | Indianapolis | IN |
| United States Rubber | Mishawaka | IN |
| Universal Atlas Cement | Gary | IN |
| University Heights Hospital | Indianapolis | IN |
| University Of Notre Dame | Indianapolis | IN |
| University Of Notre Dame | South Bend | IN |
| University Of Notre Dame | Notre Dame | IN |
| U.S. Steel | Merrillville | IN |
| U.S. Steel | Gary | IN |
| Utilities | Peru | IN |
| VA Hospital | Marion | IN |
