Pennsylvania - Area of significance: Architecture
| Madison, James, School |
| Main Building, U.S. Bureau of Mines |
| Main Library |
| Makefield Meeting |
| Malden Inn |
| Malvern Hall |
| Manayunk Main Street Historic District |
| Manchester Historic District |
| Manchester, Isaac, House |
| Manchester School No. 3 |
| Manheim Borough Historic District |
| Mann, William, School |
| Manor Street Elementary School |
| Mansfield |
| Mansfield Armory |
| Marcus Hook Plank House |
| Marietta Historic District |
| Marine Corps Depot of Supplies, Schuykill Warehouse |
| Markle Banking & Trust Company Building |
| Marklesburg Historic District |
| Marlborough Village Historic District |
| Marshall, Humphry, House |
| Marshall, Humphry, House |
| Marshall, John, School |
| Marshall, Thomas, House |
| Marshallton Historic District |
| Marshallton Inn |
| Marsh Creek Advent Church |
| Martin, B. B., Tobacco Warehouse |
| Martin Farmstead |
| Martin, James, School |
| Martin-Little House |
| Martin Orthopedic School |
| Mary Ann Furnace Historic District |
| Mary B. Sharpe School |
| Mary Immaculate Seminary (MIS) |
| Mascot Roller Mills |
| Mask and Wig Club of the University of Pennsylvania |
| Masonic Temple |
| Masonic Temple |
| Masonic Temple and Scottish Rite Cathedral |
| Massey, Thomas, House |
| Matlack, Enoch, House |
| Mauer, Dr. Joseph House |
| Maxwell, Ebenezer, House |
| Mayer Building |
| Mayer, David M., House |
| Mayfair House |
| McAllister, Archibald, House |
| McAllister-Beaver House |
| McCalls Ferry Farm |
| McCallum Manor |
| McCleary Elementary School |
| McClelland Homestead |
| McClenathan, J.C., Dr., House and Office |
| McClintock Hall |
| McClure, Alexander K., School |
| McCollum and Post Silk Mill |
| McConnell House |
| McConnellsburg Historic District |
| McCook Family Estate |
| McCormick, John B., House |
| McCoy-Shoemaker Farm |
| McDaniel, Delaplaine, School |
| McDowell Memorial Presbyterian Church |
| McFarlane, Andrew and Jennie, House |
| McGovern, Edward, Tobacco Warehouse |
| McIlvain, Francis, House |
| McKeesport National Bank |
| Meade, George, School |
| Meadville Downtown Historic District |
| Meason, Isaac, House |
| Mechanicsburg Commercial Historic District |
| Mechanicsville School |
| Mechanicsville Village Historic District |
| Media Armory |
| Meehan, Thomas, School |
| Meinig Glove Factory-Meinig, E. Richard, Co. |
| Melchinger, Englehart, House |
| Melester Barn |
| Memorial Presbyterian Church |
| Mentzer Building |
| Mercer County Court House |
| Mercer Museum |
| Mercersburg Academy |
| Mercersburg Historic District |
| Meredith, Daniel, House |
| Meredith, Simon, House |
| Meredith, Stephen, House |
| Meredith, William M., School |
| Merion Friends Meeting House |
| Merit Underwear Company |
| Merkel Mill |
| Merkel Mill Complex |
| Merrick Art Gallery |
| Merrill Lock No. 6 |
| Methodist Episcopal Church of Burlington |
| Metropolitan Edison Building |
| Mexican War Streets Historic District |
| Michael, John, Farm |
Data from United States Park Service and Wikidata
