All - Constructed - 1850–1859
| Muskegon South Pierhead Light |
| Myers-Hicks Place |
| Myrick-Yeates-Vaughan House |
| Nachusa House |
| Narraguagus Light Station |
| Nashville Children's Museum |
| National Exchange Hotel |
| Nazareth Historic District |
| Neill-Cochran House |
| Nelson, Daniel, House and Barn |
| Newark Orphan Asylum |
| New Dorp Light |
| New Dungeness Light Station |
| Newton Falls Covered Bridge |
| New Ulm High School |
| Nicking House |
| Nishnabotna Ferry House |
| Northampton County Courthouse Square |
| North Carolina State Fair Commercial & Education Buildings |
| NORTHERNER Shipwreck (Schooner) |
| North Hall, University of Wisconsin |
| North Town Hall |
| North Weare Schoolhouse |
| Oakes-Wood House |
| Oak Grove |
| Oak Grove Cemetery |
| Oak Grove Cemetery |
| Oak Hill Cemetery Chapel |
| Oakland |
| Oakland Cemetery |
| Oakland Cemetery |
| Oak Ridge Cemetery |
| Oak Ridge Military Academy Historic District |
| Oaks, The |
| Oakwood |
| Oakwood Cemetery |
| Oakwood Cemetery |
| Ocean County Jail |
| Oconee Hill Cemetery |
| Octagon House |
| Octagon House |
| Octagon House |
| Odd Fellows Rural Cemetery |
| Okauchee House |
| Old Cape May County Courthouse Building |
| Old Castle Hall, Baker University |
| Old Courthouse |
| Old Davidson County Courthouse |
| Old Executive Mansion |
| Old Homestead |
| Old Kaw Mission |
| Old Land Office Building |
| Old Lenox College |
| Old Masonic Hall |
| Old Point Loma Lighthouse |
| Old Rock School |
| Old Rock School |
| Old Slave Mart |
| Old South Union Church |
| Old Spring Tavern |
| Old St. Helena Parish Jail |
| Old Stone Church |
| Old Tuscaloosa County Jail |
| Old Wilson Historic District |
| Olive and Hurley Old School Baptist Church |
| Omaha National Bank Building |
| Ontonagon Lighthouse |
| Orange Grove Plantation House |
| Orient Baptist Church |
| Otey, William Madison, House |
| Our Lady of Sorrows Church |
| Our Lady of Sorrows Church |
| Our Mother of Sorrows Roman Catholic Church Complex |
| Pabst Brewing Company Complex |
| Packer, Asa, Mansion |
| Paddock Arcade |
| Page, H. P., House |
| Painesville Chapel |
| Palmer, Capt. Nathaniel B., House |
| Parker, Stillman, House |
| Patee, John, House |
| Patriot's Park |
| Peabody Institute Library |
| Peace College Main Building |
| Pearson, John, Soda Works |
| Pectol-Works House |
| Pedrick, Marcellus, House |
| Pensacola Lighthouse and Keeper's Quarters |
| Perham House |
| Pershing, Gen. John J., Boyhood Home |
| Pettegrove, Joshua, House |
| Phelps Library, Shattuck School |
| Philadelphus Presbyterian Church |
| Philippi Covered Bridge |
| Phinney, James, House |
| Phoenix Hall-Johnson-Harper House |
| Pierce, Carrie, House |
| Pierce Organ Pipe Factory |
| Pillow Place |
| Pilot Island Light |
Data from United States Park Service and Wikidata
