Maine - Area of significance: Politics/Government
| Salem Town House (Former) |
| Sangerville Town Hall |
| Sea Change |
| Sewall, William, House |
| Skowhegan Historic District |
| Smith, F.O.J., Tomb |
| Somerset County Courthouse |
| Squire Tarbox House |
| Stewart Free Library |
| Surry Town Hall |
| Tate House |
| """The Rim"" and Site of Fort Foster" |
| Tranquility Grange No. 344 |
| Treat, Nathaniel, House |
| Turner Town House |
| Ulmer, George, House |
| Underwood, Joseph H., House |
| Union Church |
| Union Church, (former) |
| Union Hall |
| Union Meeting House, (Former) |
| Union Town House (Former) |
| Upper Dallas School |
| Upton Grange No. 404 (Former) |
| U.S. Customhouse |
| U.S. Inspection Station-Calais (Ferry Point), Maine |
| U.S. Inspection Station-Coburn Gore, Maine |
| U.S. Inspection Station-Fort Fairfield, Maine |
| U.S. Inspection Station-Limestone, Maine |
| U.S. Inspection Station-Orient, Maine |
| Vaughan Homestead |
| Washburn, Gov. Israel, House |
| Waterville Opera House and City Hall |
| Wayne Town House |
| Webb River Grange |
| Weld Town Hall |
| Wentworth, Mark F. and Eliza J., House |
| West Market Square Historic District |
| White, James P., House |
| Wiley, James Sullivan, House |
| Winthrop Street Historic District |
| Wiscasset Jail and Museum |
| Woolwich Town House |
| York Historic District |
Data from United States Park Service and Wikidata
