Maine - Area of significance: Commerce
| Observer Building |
| Old Post Office |
| Old Red Store |
| Owls Head Light Station |
| Parsons, Josiah K., Homestead |
| Patten Building |
| Peck, Bradford, House |
| Pejepscot Paper Company |
| Pemaquid Restoration and Museum |
| Pendleton, James G., House |
| Pennellville Historic District |
| Poland Spring Bottling Plant and Spring House |
| Porteous, Mitchell and Braun Company Building |
| Portland Breakwater Light |
| Portland Headlight |
| Portland Waterfront |
| Presque Isle National Bank |
| Primrose Hill Historic District |
| Rangeley Trust Company Building |
| Rankin Block |
| Reed, G. W., Travellers Home |
| Richardson House |
| Richmond Historic District |
| Roak Block |
| Rockland Breakwater |
| Rockland Breakwater Lighthouse |
| Rockport Historic District |
| Rockport Historic Kiln Area |
| Rose, Robert, Tavern |
| Ruggles House |
| Rumford Commercial Historic District |
| Rumford Falls Power Company Building |
| Saco Historic District |
| Sail Loft |
| Savings Bank Block |
| Searsport Historic District |
| Seguin Island Light Station |
| Shore Acres |
| Skowhegan Historic District |
| Songo Lock |
| Southard Block |
| Spring Street Historic District |
| Sproul's Cafe |
| Standish Corner Historic District |
| Staples Inn |
| STEPHEN TABER (schooner) |
| Strathglass Building |
| Stroudwater Historic District |
| Tate House |
| The Birches |
| Thomaston Historic District |
| Tracy-Causer Block |
| Two Cent Bridge |
| Union Hotel |
| U.S. Customhouse and Post Office |
| Vickery Building |
| Walking Man Sign |
| Water Street |
| Waterville Main Street Historic District |
| Waterville Main Street Historic District |
| Way Way General Store |
| Wheelwright Block |
| Winterport Historic District |
| Winthrop Street Historic District |
| Wiscasset Historic District |
| Woodman Building |
| York Historic District |
Data from United States Park Service and Wikidata
