All - Constructed - 1840–1849
| Mississippi Governor's Mansion |
| Monmouth Street Historic District |
| Monteith,Thomas and Walter,House |
| Montgomery-Janes-Whittaker House |
| Montrose |
| Moore House |
| Morrison, Robert Harvey, Farm and Pioneer Mills Gold Mine |
| Mount de Chantal Visitation Academy |
| Mount Hebron Cemetery and Gatehouse |
| Mount Holly Cemetery |
| Mount Pleasant Cemetery |
| Mouton, Charles H., House |
| Moyce-Steffens House |
| Mt. Albion Cemetery |
| Mt. Horeb Presbyterian Church and Cemetery |
| Munroe, Robert, House |
| Muskego Church |
| Mutual Benefit Life Insurance Company |
| New London Railroad Station |
| Newton, S.D., House |
| New York Shakespeare Festival Public Theater |
| North Avenue Congregational Church |
| Northcutt Plantation |
| North Rochester Congregational Church |
| North School |
| North Star School District No. 11 |
| Oakland |
| Oakland |
| Oakland Grove Presbyterian Church |
| Oak Ridge |
| O'Brien-Peuschel Farmstead |
| Ochlocknee Missionary Baptist Church and Cemetery |
| O'Conor, Andrew J., III, House |
| Odd Fellows Hall |
| Old Bergen Church |
| Old Fort House |
| Old Main |
| Old Naval Observatory |
| Old Presque Isle Lighthouse |
| Old St. Mary's Church |
| Old Tavern |
| Old Town |
| Old Town Bridge |
| Oliver, Capt. John, House |
| Olive, Richard, House |
| Otis Company Mill No. 1 |
| Our Lady of Peace Cathedral |
| Paddock-Hubbard House |
| Palmer Island Light Station |
| Palmetto Farm |
| Parker, Harrison, Sr., House |
| Parsons, Ambrose, House |
| Parsons-Piper-Lord-Roy Farm |
| Payne Hotel |
| Pearson, Franklin, House |
| Peck, John M., House |
| Peekskill Presbyterian Church |
| Pena Adobe |
| Pender, Joseph John, House |
| Pike, Abram W., House |
| Pine Creek Gristmill |
| Pistol Factory Dwelling |
| Pitts, Samuel R., Plantation |
| Plainfield Town Hall |
| Pleasant Run Stone House I |
| Pleasant Street Congregational Church |
| Pleasant Valley Methodist Church |
| Plummer, Capt. John, House |
| Pointe Aux Barques Lighthouse |
| Porth, Dr. Joseph P. and Effie, House |
| Port Washington Light Station |
| Pratt, Stillman, House |
| Prescott, Gustavus G., House |
| Preston House |
| Punahou School Campus |
| Punchard, Benjamin House |
| Queen Emma's Summer Home |
| Raiford, Robert, Home and Farm |
| Rally Hill |
| Ramsey House |
| Rancho Canada de los Osos y Pecho y Islay |
| Rancho El Encino |
| Rancho San Lucas |
| Rankin, John, House |
| Record, E.C. and M.I., Homestead |
| Red Oak Creek Covered Bridge |
| Reedy Rill |
| Rice-Tremonti House |
| Richardson-Brinkman Cobblestone House |
| Rich, Charles B., House |
| Riley, James Whitcomb, House |
| Riverside Farm |
| Robbins, Joseph, House |
| Rock Island Light Station |
| Rose Hill |
| Rose Hill |
| Roseneath |
| Row House |
| Row, The |
| Russian Bishop's House |
Data from United States Park Service and Wikidata
