Ohio - Area of significance: Social History
| House, Col. Erastus, House |
| Hubbard, Col. William, House |
| Hulburt, Halsey, Homestead |
| Hull, Isaac, Store |
| Hull-Wolcott House |
| Huntington, John, Pumping Tower |
| Huron County Children's Home |
| Ikirt House |
| Independent Order of Oddfellows, Dayton Lodge No. 273 |
| Independent Order of Odd Fellows Temple |
| Ingersoll, Cyrus J., House |
| Inglewood Historic District |
| Insco Apartments Building |
| Irishtown Bend Archeological District |
| Jackson, Andrew, House |
| Jacob's Church |
| Jersey Independent Order of Odd Fellows Hall |
| John, Jehu, House |
| Johnson, E. J., House |
| Johnson, John, Farm |
| Jones, Elam, Public House |
| Joseph and Feiss Clothcraft Shops, The |
| Karrer, Henry, House |
| Kelleys Island South Shore District |
| Kellogg, John, House and Barn |
| Kemp, Lewis, House |
| Kendall, Virginia, State Park Historic District |
| Kenton Public Library |
| Kerper and Melbourne Terrace Apartments |
| Kilbourn, William, House |
| Kilpi Hall |
| King Records Studio Buildings |
| Knapp, William, House |
| Knights of Pythias Hall |
| Knowlton, Dr. William A., House |
| Koehne-Poast Farm |
| Kossuth Colony Historic District |
| Krause Building-Otto Moser's Cafe |
| Lafayette Lodge No. 79 |
| Lagonda Club Building |
| Lake Shore Bank and Cleveland Public Library St. Clair Branch |
| Lakeside Historic District |
| Lancaster Methodist Episcopal Camp Ground Historic District |
| Langston, John Mercer, House |
| Laughlin, Homer, House |
| Laurel Homes Historic District |
| League Park |
| Lewis, Dr. A. C., House |
| Lima Memorial Hall |
| Linden Community and Recreation Center |
| Lorain YMCA Building |
| Lucas County Hospital and Nurse's Home |
| Lundy, Benjamin, House |
| Macedonia Church |
| Madison Seminary And Home |
| Mad River Block |
| Manse Hotel and Manse Hotel Annex |
| Maple-Dell |
| Maplewood |
| Marion Cemetery Receiving Vault |
| Marion Women's Club Home |
| Marsh, George H., Homestead and the Marsh Foundation School |
| Marvin Memorial Library |
| Masonic Lodge #472 |
| Masonic Temple |
| Masonic Temple |
| Masonic Temple |
| Masonic Temple |
| Masonic Temple Building |
| Masonic Temple Price Hill Lodge, No. 524 |
| Mason, John Wesley, Gothic Cottage |
| Mattoon-Woodrow House |
| May 4, 1970, Kent State Shootings Site |
| May, David and Mary, House |
| McCorkle, Almon G., House |
| McDowell, Austin, House |
| McKay, Moses, House |
| McKinley Park Apartments |
| McKisson, Robert, House |
| McKitrick, Dr., House |
| McKitrick, Dr., Office |
| McLain-Gillmer House |
| Mecklenburg's Garden |
| Medfair Heights Apartment Historic District |
| Medina Masonic Temple and Medina Theater |
| Mellett-Canton Daily News Building |
| Melville-Milne, William Gordon, House |
| Memorial Hall |
| Mendon Town Hall |
| Mentor Avenue District |
| Middle Bass Club Historic District |
| Middleport Public Library |
| Milan Historic District |
| Miles Park Historic District |
| Miller, Lewis, House |
| Monteith Hall |
| Morgan Township House |
| Mosgrove, Dr. Adam, House |
| Moss-Foster House |
| Mother Thompson House |
Data from United States Park Service and Wikidata
