Washington - Significance region: Local
| Leamington Hotel and Apartments |
| Leary, Eliza Ferry, House |
| Leonard, T. A., Barn |
| Leopold Hotel |
| Lester Depot |
| Levesque-Majer House |
| Lewis & Clark High School |
| Lewis County Courthouse |
| Lewis, Hannah, House |
| Lewisville Park |
| Liberty Theater |
| Liggett Building |
| Lincoln Hotel |
| Lincoln School |
| Lincoln Theater and Commercial Block |
| Lindsey, William, House |
| Littlebrook |
| Little Red Schoolhouse |
| Loers, Benjamin, House |
| Longbranch School Gymnasium |
| Longfellow Elementary School |
| Long Lake Recreation Hall |
| Long, Robert Alexander, High School |
| Longview Community Church |
| Longview Community Church-Saint Helen's Addition |
| Longview Community Store |
| Longview Women's Clubhouse |
| Loomis House |
| Loon Lake School |
| Lord, C. J., Mansion |
| Lord-Heuston House |
| Lord, Richard Hinton, House |
| Lotz, J. H., House |
| Lowe, David, House |
| Lucerne Guard Station |
| Ludwigs, George, House |
| Luepke Florist |
| Lumber Exchange Building |
| Lund Building |
| Lutheran St. Paul's Kirche |
| Lynden Department Store |
| Lynn, C.O., Co. Funeral Home |
| Lyon Building |
| Lytle, Joseph, Home |
| Mabton High School |
| Magnolia Public Library |
| Malaney-O'Neill House |
| Maloney's General Store |
| Manito Park and Boulevard |
| Manley-Thompson Ford Agency |
| Manresa Hall |
| Marcus Whitman Hotel |
| Marine Supply and Hardware Complex |
| Marshall Bridge |
| Marsh, Louis S., House |
| Marymoor Prehistoric Indian Site |
| Mary Queen of Heaven Roman Catholic Church |
| Marysville Opera House |
| Mason County Courthouse |
| Masonic Hall |
| Masonic Hall- Port Orchard |
| Masonic Lodge Building |
| Masonic Temple |
| Masonic Temple |
| Masonic Temple-Auburn |
| Masonic Temple Building-Temple Theater |
| Masonic Temple-Hoquiam |
| Matzen, George and Irene, House |
| McAllister, Alexander, House |
| McCabe Building |
| McCauley, H. M., House |
| McCleary, Henry, House |
| McCleary Hotel, Old |
| McGrath Cafe and Hotel-The McGrath |
| McIlvaine Apartments |
| McKinley School |
| McMillen-Dyar House |
| McMillin School |
| McTaggert, Lachlin, House |
| Medical Dental Building |
| Meese, Gustav, Building |
| Metaline Falls School |
| Methodist Epscopal Church of Port Hadlock |
| Meyer, Heye H. and Eva, Farmstead |
| Meyer House |
| Meyers Falls Power Plant Historic District |
| Michael's Cabin |
| Mickelson, Ole, Cabin |
| Midway School |
| Miller, Alexander, House |
| Miller Block |
| Miller-Brewer House |
| Miller, George, House |
| Miller, John J., House |
| Millersylvania State Park |
| Mill House |
| Millionaire’s Row Historic District |
| Mills Building |
| Millwood Historic District |
| Milwaukee Road Bunkhouse |
Data from United States Park Service and Wikidata
