Pennsylvania - Criteria: A (event)
| Logan Mills Gristmill |
| Logans Ferry Powder Works Historic District |
| Logan Square |
| Log House, Hiester House, and Market Annex |
| Loller Academy |
| Longfellow School |
| Long-Hawerter Mill |
| Long Meadow Farm |
| Longue Vue Club and Golf Course |
| Longwood Gardens District |
| Lord House |
| Lorraine Apartments |
| Loux Covered Bridge |
| Lovell Manufacturing Company |
| Lower Humbert Bridge |
| Lower Merion Academy-Cynwyd Elementary School-Bala Cynwyd Junior High School Complex |
| Lower North Philadelphia Speculative Housing Historic District |
| Lower Swedish Cabin |
| Lumberville Historic District |
| Lunn's Tavern |
| Lupfer, Israel and Samuel, Tannery Site and House |
| Lutheran Theological Seminary-Old Dorm |
| Lutz, John F., Furniture Co. & Funerary |
| Luzerne County Fresh Air Camp |
| Luzerne Presbyterial Institute |
| Lyle Covered Bridge |
| Madison Elementary School |
| Makefield Meeting |
| Manasses Guth Covered Bridge |
| Manayunk Main Street Historic District |
| Manchester, Isaac, House |
| Manheim Borough Historic District |
| Manor Street Elementary School |
| Mansfield |
| Mansfield Armory |
| Marianna Historic District |
| Marine Barracks |
| Marine Corps Depot of Supplies, Schuykill Warehouse |
| Marine Corps Supply Activity |
| Markle Banking & Trust Company Building |
| Marklesburg Historic District |
| Marlborough Village Historic District |
| Marshallton Historic District |
| Marshallton Inn |
| Martin, B. B., Tobacco Warehouse |
| Martin Orthopedic School |
| Martin's Mill Covered Bridge |
| Martin's Mill Covered Bridge |
| Martin Tower |
| Mary Ann Furnace Historic District |
| Mascot Roller Mills |
| Mask and Wig Club of the University of Pennsylvania |
| Massey, Thomas, House |
| Mauch Chunk and Summit Hill Switchback Railroad |
| Mays, Blaney Covered Bridge |
| McCalls Ferry Farm |
| McClelland-Grimes Farm |
| McCollum and Post Silk Mill |
| McConnellsburg Historic District |
| McConnell's Mill Covered Bridge |
| McCoy-Shoemaker Farm |
| McGees Mills Covered Bridge |
| McGovern, Edward, Tobacco Warehouse |
| McKeesport National Bank |
| Meadville Downtown Historic District |
| Mechanicsburg Commercial Historic District |
| Mechanicsville Village Historic District |
| Media Armory |
| Melrose |
| Memorial Fountain and Statue |
| Mennonite Meetinghouse |
| Mentzer Building |
| Mercer County Court House |
| Mercersburg Academy |
| Mercer's Mill Covered Bridge |
| Merion Cricket Club |
| Merion Friends Meeting House |
| Merion Golf Club, East and West Courses |
| Merit Underwear Company |
| Merkel Mill |
| Merkel Mill Complex |
| Merrick Art Gallery |
| Merrill Lock No. 6 |
| Metropolitan Edison Building |
| Metropolitan Opera House |
| Metz Ice Plant |
| Michael, John, Farm |
| Michener, Nathan, House |
| Middishade Clothing Factory |
| Middle Pickering Rural Historic District |
| Midtown Harrisburg Historic District |
| Mifflinburg Historic District |
| Mifflin Elementary School |
| Mifflin School |
| Mikado Freight Locomotive No. 520 |
| Mikveh Israel Cemetery |
| Milanville Historic District |
| Milford Historic District |
| Mill at Lobachsville |
| Mill Creek Historic District |
Data from United States Park Service and Wikidata
