All - Architectural style - Federal architecture
| Lemon, James, Houses |
| Lenhart Farmhouse |
| Lenox Academy |
| Lenthall Houses |
| Leonard, Capt. Charles, House |
| LeRay Hotel |
| LeRoy, Daniel, House |
| Level Loop |
| Leverton, Jacob and Hannah, House |
| Lewis-Capehart-Roseberry House |
| Lewis, Edward Simon, House |
| Lexington and Covington Turnpike Toll House |
| Libby-MacArthur House |
| Liberia |
| Liberty Farm |
| Liberty Hall |
| Liberty Hall |
| Lincoln, Ambrose, Jr., House |
| Lincoln, Gen. Thomas, House |
| Lincoln Homestead and Cemetery |
| Lincoln, Mordecai, House |
| Lincolnville Center Meeting House |
| Linden |
| Linden |
| Linden Flats |
| Linden House |
| Little Cherrystone |
| Little, Edward, House |
| Littlefield, Hamilton and Rhoda, House |
| Little House |
| Little Manor |
| Littlepage Stone Mansion |
| Livingston Parish Courthouse, Old |
| Loats Female Orphan Asylum of Frederick City |
| Lochiel Farm |
| Locke, Capt. Josiah, House |
| Locke, Lt. Benjamin, Store |
| Lockkeeper's House, C & O Canal Extension |
| Lockwood-Boynton House |
| Locust Avenue |
| Locust Grove |
| Locust Grove |
| Locust Grove |
| Locust Grove |
| Locust Grove |
| Locust Grove |
| Locust Hill |
| Locust Lawn Estate |
| Locust Level |
| Long Meadow |
| Long Meadow |
| Longstreet Farm |
| Longwood |
| Loomis-Pomeroy House |
| Lord, Capt. Nathaniel, Mansion |
| Lord-Dane House |
| Lord Mansion |
| Losee, John, House |
| Lothrop, Caleb, House |
| Lothrop, Joseph, House |
| Lovell, Capt. George, House |
| Lowe, Joshua, House |
| Lower Louviers and Chicken Alley |
| Lower Merion Academy-Cynwyd Elementary School-Bala Cynwyd Junior High School Complex |
| Low House |
| Lowry, William C., House |
| Lowry, William, House |
| Low, Thomas, House |
| Lowville Presbyterian Church |
| Lucas, Jonathan, House |
| Lucky Hit |
| Ludlam, Henry, House |
| Ludlow-Van Rensselaer House |
| Mace, Henry, House |
| Macksville Tavern |
| Macomber Stone House |
| Maddux House |
| Maden Hall Farm |
| Madison Masonic Lodge |
| Magnolia Grange |
| Magnolia Hill |
| Magnolia Plantation |
| Magowan, Abraham, House |
| Maguire, Patrick, House |
| Maidstone-on-the-Potomac |
| Maine State House |
| Main Street Friends Meeting House |
| Maizefield |
| Makepeace, George, House |
| Malvern |
| Manasseh Cutler Hall, Ohio University |
| Mangum, James, House |
| Mann, Andrew, Inn |
| Mann, Donald, House |
| Manning, Richard, House |
| Manor House |
| Manse, The |
| Maple Roads |
| Maples Cottage |
| Maplewood |
Data from United States Park Service and Wikidata
