Ohio - Role: District
| Kossuth Colony Historic District |
| Kulas, E. J., Estate Historic District |
| Lake Ridge Island Mounds |
| Lakeside Historic District |
| Lakewood Downtown Historic District |
| Lancaster Historic District |
| Lancaster Methodist Episcopal Camp Ground Historic District |
| Lancaster West Main Street Historic District |
| Lane's Mill Historic Buildings |
| Laurel Homes Historic District |
| Law, Henry, Farm Historic District |
| Lebanon Commercial District |
| L. Hoster Brewing Company |
| Limbach Block Historic District |
| Lisbon Historic District |
| Lockington Locks Historical Area |
| Logan Historic District |
| London Commercial Business Historic District |
| Lorain Avenue Commercial Historic District |
| Lorain Station Historic District |
| Louisville Historic District |
| Lower Price Hill Historic District |
| Lower Prospect-Huron Historic District |
| Ludowici Roof Tile Company Historic District |
| Ludwig, Isaac R., Historical Mill |
| Lyceum Village Square And German Wallace College |
| Lytle Park Historic District |
| Mackinaw Historic District |
| Madison and Woodburn Historic District |
| Madison Avenue Historic District |
| Madison-Stewart Historic District |
| Magnolia-Wade Park Historic District |
| Mahoning Avenue Historic District |
| Main Exchange Historic District |
| Main-Market Historic District |
| Main Street Commercial Historic District |
| Main Street Historic District |
| Main Street Historic District |
| Main Street Historic District |
| Main-Third Street Buildings |
| Malabar Farm |
| Mantua Center District |
| Mantua Station Brick Commercial District |
| Mariemont Historic District |
| Marietta Historic District |
| Marion Downtown Historic District |
| Market Square |
| Marysville Historic District |
| Massillon Downtown Historic District |
| Mather, Flora Stone, College District |
| Maumee Historic District |
| Maumee Uptown Historic District |
| Mayfield Heights Historic District |
| McConnelsville Historic District |
| McDonald Farm |
| McIntire Terrace Historic District |
| McPherson Town Historic District |
| Mechanicsburg Commercial Historic District |
| Medfair Heights Apartment Historic District |
| Medina Public Square Historic District |
| Mentor Avenue District |
| Mesopotamia Village District |
| Metzger, Charles, Mound |
| Miami-Erie Canal Site Historic District |
| Miami Monthly Meeting Historic District |
| Miami Valley Golf Course and Clubhouse |
| Middle Bass Club Historic District |
| Midtown Historic District |
| Milan Historic District |
| Miles Park Historic District |
| Mill Creek Park Historic District |
| Mill & Dunn Historic District |
| Millersburg Historic District |
| Mitchell Historic District |
| Moar Mound And Village |
| Mohawk Place Historic District |
| Monroe Street Commercial Buildings |
| Morristown Historic District |
| Mound City Group National Monument |
| Mount Airy Forest |
| Mount Auburn Historic District |
| Mount Pleasant Historic District |
| Mount Sterling Historic District |
| Mount Union College District |
| Mount Victory Historic District |
| Mt. Nebo Archeological District |
| Muskingum College Campus Historic District |
| Muskingum River Lock No. 10 And Canal |
| Muskingum River Navigation Historic District |
| Myrtle-Highview Historic District |
| National Orphans' Home, Junior Order United American Mechanics |
| Near Northside Historic District |
| Nela Park |
| Nelsonville Historic District |
| Newark Downtown Historic District |
| New Indianola Historic District |
| Newport Village Allotment Historic District |
| Newton Avenue Historic District |
| Ninth Street Historic District |
| North Broadway Historic District |
Data from United States Park Service and Wikidata
