All - Constructed - 1860–1869
| Old Linn County Jail |
| Old LSU Site |
| Old Main |
| Old Pilgrim Baptist Church Cemetery and Kilgore Family Cemetery |
| Old Plover Methodist Church |
| Old Schwamb Mill |
| Old St. Patrick's Church |
| Old Synagogue |
| Olive Branch Methodist Episcopal Church |
| Olive Township District No. 1 School |
| Onondaga County Savings Bank Building |
| Opp Cottage |
| Oquawka Wagon Bridge |
| Oregon Creek Covered Bridge |
| Oroville Chinese Temple |
| Our Lady of Guadalupe Church and Medina Cemetery |
| Overmyer-Waggoner-Roush Farm |
| Ownby, John, Cabin |
| Packard-Doubler House |
| Paddock, Henry I., House |
| Page-Walker Hotel |
| Paine, Robert Treat, Jr., House |
| Palmer, Gen. Joseph B., House |
| Palmyra Methodist Episcopal Church |
| Pardee House |
| Pardeeville Presbyterian Church |
| Paris Cemetery Gatehouse |
| Parkview Community Ditch |
| Patten Building |
| Paull, Alfred, House |
| Pawtucket Congregational Church |
| Peabody Library |
| Pejepscot Paper Company |
| Pembroke Mill |
| Pendleton House |
| Peninsula Point Lighthouse |
| Penn Center Historic District |
| Penniman, Edward, House and Barn |
| Perry, Clark, House |
| Peters, A. V., House |
| Peterson, Andrew, Farmstead |
| Phillips Memorial Auditorium |
| Pineview |
| Piney Prospect |
| Pinos Altos Historic District |
| Pisgah United Methodist Church and Cemetery |
| Pleasant Valley Wine Company |
| Plumbush |
| Plum Street Temple |
| Point Douglas-St. Louis River Road Bridge |
| Pond Creek Station |
| Poppenhusen Institute |
| Port Royal House |
| Potter and Barker Grain Elevator |
| Prescott, C. J., House |
| Prince Hall Mystic Cemetery |
| Prospect Heights Historic District (Boundary Increase) |
| Prospect Park |
| Public School 111 and Public School 9 Annex |
| Purefoy-Chappell House and Outbuildings |
| Quarries of the Hummelstown Brownstone Company |
| Rackleff Building |
| Raleigh National Cemetery |
| Ramsey, Alexander, House |
| Ratterman, Bernard, House |
| Rattermann, Heinrich A., House |
| Rawson Estate |
| Red Covered Bridge |
| Reed Hall |
| Reed Opera House and McCornack Block Addition |
| Reitman's St.Joseph House |
| Reno Southern Pacific Railroad Depot |
| Reynolds, Isaac N., House |
| Rhodes House |
| Richards House |
| Richwood Methodist Church |
| Riggs, Samuel A., House |
| Ringos Mill Covered Bridge |
| Roberts-Carter House |
| Rob Roy Covered Bridge |
| Rock Island Arsenal |
| Roth Farm |
| Rowley, Dr. Newman C., House |
| Rugby Grange |
| Russell County Courthouse at Seale |
| Russell, Rensselaer, House |
| Sail Loft |
| Salt Works Ranch |
| Sand Point Lighthouse |
| Sandy Pond School |
| San Jose Church |
| Saugerties Lighthouse |
| Sauk City Fire Station |
| Sautter, John, Farmhouse |
| Scarlet Oaks |
| Schoolcraft Furnace Site |
| Schoolhouse |
| Schuebeler, Charles, House |
| Sea Cliff Railroad Station |
| Senter-Rooks House |
Data from United States Park Service and Wikidata
