Ohio - Area of significance: Architecture
| Huntington Grange |
| Huntington Inn, Old |
| Huntington, John, Pumping Tower |
| Huntington Public School |
| Huntington Township Hall |
| Hunt-Wilke Farm |
| Huron County Children's Home |
| Huron County Courthouse And Jail |
| Huron Harbor Light |
| Huron School |
| Huron-Superior Streets Warehouse-Produce Historic District |
| Hurst, William E., House |
| Hurth Hotel |
| Hyde Park Methodist Episcopal Church |
| Ideal Department Store Building |
| Idora Park |
| Ijams, Joseph, House |
| Ikirt House |
| Immaculate Conception Catholic Church Complex |
| Immaculate Conception Church |
| Immaculate Conception Church, School, and Rectory |
| Immaculate Conception Rectory at Botkins |
| Imperial Glass Company |
| Independence Presbyterian Church |
| Independent Order of Oddfellows, Dayton Lodge No. 273 |
| Independent Order of Odd Fellows Temple |
| Independent School District No. 2 Building |
| Indianola Junior High School |
| Indian Run Cemetery Stone Walls |
| Ingalls Building |
| Ingersoll, Cyrus J., House |
| Inglewood Historic District |
| Insco Apartments Building |
| Inselruhe |
| Ira Apartments |
| Ireland, Joseph, House |
| Irishtown Bend Archeological District |
| Isham, John, Farmstead |
| Isham, John, House |
| Island House |
| Iuka Ravine Historic District |
| Iutzi, Christian, Farm |
| Izant, Grace Goulder, House |
| Jackson, Andrew, House |
| Jacob's Church |
| Jacobs, Felix A., House |
| Jaeger Machine Company Office Building |
| Jamestown Opera House |
| Jarvis House |
| Jay's Lunch |
| Jefferson Avenue Historic District |
| Jefferson Schoolhouse |
| Jeffrey Manufacturing Company Office Building |
| Jenkins-Perry House |
| Jennings Apartments |
| John, Jehu, House |
| Johnson-Campbell House |
| Johnson, Dustin, Residence |
| Johnson-Humrickhouse House |
| Johnson Steel Street Railway Company General Offices Building |
| Johnson, Thomas, House |
| Johnston-Crossland House |
| Johnstown Jail |
| Jones-Bowman House |
| Jones-Cutler House |
| Jones, Elijah Pelton, House |
| Jones Hall, Youngstown State University |
| Jones Home for Children |
| Jones Home Subdivisions Historic District |
| Jones, John J., House |
| Jones-Read-Touvelle House |
| Jones, W. H., Mansion |
| Joseph-Cherrington House |
| Joyce, Jacob O., House |
| Judy Chapel |
| Julienne Girls Catholic High School |
| Jyurovat Farmstead |
| Kahiki, The |
| Kaiser, John, House |
| Karrer Barn |
| Karrer, Henry, House |
| Kauber, Warren F., Funeral Home |
| Kauffman, Linus B., House |
| Kaufman, Frank J., House |
| Kearns, George and Edward, Houses |
| Keeler, Diadatus, House |
| Kelley, Barney, House |
| Kelleys Island South Shore District |
| Kelley, William, Hardware Store-Hayesville Odd Fellows Hall |
| Kellogg House |
| Kellogg, John, House and Barn |
| Kelly Family Home |
| Kemp, Lewis, House |
| Kendall, Virginia, State Park Historic District |
| Kendel Building |
| Kenilworth Avenue Historic District |
| Kennedy Apartments and Commercial Block |
| Kennedy Stone House |
| Kennel, John, Jr., Farm |
| Kennel, John Sr., Farm |
Data from United States Park Service and Wikidata
