Ohio - Criteria: B (person)
| Looker, Othniel, House |
| Luethstrom-Hurin House |
| Lundy, Benjamin, House |
| Lunkenheimer, Frederick, House |
| MacDonell House |
| Mackinaw Historic District |
| Madam Fredin's Eden Park School and Neighboring Row House |
| Malabar Farm |
| Maltby, Henry, House |
| Maple-Dell |
| March, George, House |
| Marmon, Martin, House |
| Marshall, James E., House |
| Marsh, George H., Homestead and the Marsh Foundation School |
| Mason, Frank H., House |
| Masonic Temple |
| Mattoon-Woodrow House |
| McClelland, Harry S., House |
| McCook, Daniel, House |
| McCorkle, Almon G., House |
| McCracken-McFarland House |
| McCracken-Scott House |
| McGuffey, William H., Boyhood Home Site |
| McGuffey, William H., House |
| McKinley Memorial |
| McKinley, William, Tomb |
| McKitrick, Dr., House |
| McKitrick, Dr., Office |
| McLain-Gillmer House |
| McPherson, Maj. Gen. James B., House |
| McSweeney, John, House |
| Mead House |
| Medill, William, House |
| Meeker, Forrest, House and Farm |
| Merriman, Wells E., House |
| Miles, Enos, House |
| Miller, Lewis, House |
| Miller, Peter, House |
| Miner's Supply Store |
| Mitchell, Charles, House |
| Mitchell, Randolph, House |
| Monteith Hall |
| Montgomery County Courthouse |
| Mooney, William C., House |
| Moore, Charles H., House |
| Moore, Edward W. and Louise C., Estate |
| Moore, Leonard M., House |
| Morgan, John H., Surrender Site |
| Morgan Mansion |
| Morrow-Overman-Fairley House |
| Mosgrove, Dr. Adam, House |
| Moss-Foster House |
| Mott Drug Store |
| Mound House |
| Mountain House |
| Mount Auburn Historic District |
| Mueller, Christ, House |
| Mumma, Jacob H. W., House |
| Munson, Judge Albert, House |
| Myers Hall |
| New England Lodge |
| Newman, William, House |
| Newton, Judge Eben, House |
| Nicholson, James, House |
| Ninchelser, Dr., House |
| Ninth Street Historic District |
| Noble, Jonathan, House |
| Normandy Farms |
| Northrop, Julia Carter, House |
| Nurre-Royston House |
| Ohio Company Land Office |
| Ohio University Campus Green Historic District |
| Ohmer, Nicholas, House |
| Old West End District |
| Olive Furnace |
| Olney, Charles, House and Gallery |
| Oregon Historic District |
| Orton Memorial Laboratory |
| Osborn, Charles S., House |
| Overfield Tavern |
| Packard, James Ward, House |
| Parker, John P., House |
| Parmelee House |
| Pease Homestead |
| Pendleton, George Hunt, House |
| Peters-Kupferschmid House |
| Piatt, Abram S., House and Piatt, Donn S., House |
| Pierce, Elijah, Properties |
| Pinecroft |
| Pinney, Dr. Eli, House |
| Piqua Historical Area State Memorial |
| Pitman, Ben, House |
| Plainview Farm |
| Pleasant Hill |
| Pollack, Isaac, House |
| Pomerene House |
| Pomeroy, Alanson, House |
| Porter, Orin, House |
| Powell, Andrew, Homestead |
| Pringle-Patric House |
Data from United States Park Service and Wikidata
