Maine - Criteria: A (event)
| Norlands, The |
| Norridgewock Female Academy |
| Norridgewock Free Public Library |
| North Berwick Woolen Mill |
| North Jay Grange Store |
| North Monmouth Library |
| North School |
| North Waterford Congregational Church |
| North Yarmouth Academy |
| North Yarmouth and Freeport Baptist Meetinghouse |
| Norton's Corner School |
| Norway Historic District |
| Nutting Homestead, The |
| Oakfield Station |
| Oakland Public Library |
| Observer Building |
| Ocean Park Historic Buildings |
| Odd Fellows-Rebekah Hall |
| Off-the-Neck Historic District |
| Ogunquit Playhouse |
| Old Grist Mill |
| Old Hancock County Buildings |
| Old Post Office |
| Old Schoolhouse |
| Old Tavern |
| Old Town House |
| Old Union Meetinghouse |
| Olson House |
| Olsson, Anders and Johanna, Farm |
| Orono Main Street Historic District |
| Otisfield Town House (Former) |
| Otisfield Town Pound |
| Our Lady of Mount Carmel Catholic Church |
| Owls Head Light Station |
| Paine Neighborhood Historic District |
| Paris Hill Historic District |
| Paris Public Library |
| Park Street Row |
| Parsonsfield Seminary |
| Parsons-Piper-Lord-Roy Farm |
| Patten Building |
| Paul Family Farm |
| Peabody-Fitch House |
| Peabody Tavern |
| Pejepscot Paper Company |
| Pemaquid Point Light |
| Pemaquid Restoration and Museum |
| Pendle Hill |
| Pennell Institute |
| Pennellville Historic District |
| Penobscot Marine Museum |
| Penobscot Salmon Club and Pool |
| Percy and Small Shipyard |
| Perkins Island Light Station |
| Perley, Sam, Farm |
| Petit Manan Light Station |
| Pettengill House and Farm |
| Phi Gamma Delta House |
| Philler Cottage |
| Pike, LeRoy F., Memorial Building |
| Pittsfield Railroad Station |
| Pittston Farm |
| Pleasant River Grange No. 492 |
| Poland Spring Beach House, (Former) |
| Poland Spring Bottling Plant and Spring House |
| Poland Spring Historic District |
| Pond Meeting House |
| Porteous, Mitchell and Braun Company Building |
| Porter Old Meetinghouse |
| Porter-Parsonfield Bridge |
| Portland Breakwater Light |
| Portland City Hospital |
| Portland Headlight |
| Portland High School |
| Portland Observatory |
| Portland Packing Company Factory |
| Portland Railroad Company Substation |
| Portsmouth Company Cotton Mills: Counting House |
| Portsmouth Naval Shipyard |
| Powder House Lot |
| Powers House |
| Pownalborough Courthouse |
| Pownal Cattle Pound |
| Presque Isle National Bank |
| Primrose Hill Historic District |
| Prospect Harbor Light Station |
| Pumpkin Island Light Station |
| Purinton Family Farm |
| Putnam, Blackhawk, Tavern |
| Pythian Opera House |
| Quincy Building |
| Rackleff Building |
| Ram Island Ledge Light Station |
| Ram Island Light Station |
| Randall, Jacob, House |
| Rangeley Tavern |
| Rangeley Trust Company Building |
| Rangley Public Library |
| Rankin Block |
| Readfield Union Meeting House |
Data from United States Park Service and Wikidata
