Pennsylvania - Significance region: Local
| Mountain Meadow Farm |
| Mountain Springs Hotel |
| Mount Airy Historic District |
| Mount Pleasant Historic District |
| Mount Pleasant Historic District |
| Mount Saint Mary Convent and Saint Benedict Academy Historic District |
| Mount St. Peter Roman Catholic Church |
| Mount Tabor AME Zion Church and Cemetery |
| Mount Union Historic District |
| Moxham Historic District |
| Moyer, John Nicholas and Elizabeth, House |
| Mt. Airy Station |
| Mt. Alvernia Historic District |
| Mt. Lebanon Historic District |
| Mt. Pleasant Iron Works House |
| Muddy Creek Bridge, Maryland and Pennsylvania Railroad |
| Muddy Creek Forks Historic District |
| Muhlenberg School |
| Muhr, Simon, Work Training School |
| Mulford Building |
| Mulford, Sylvanus, House |
| Mumma, Samuel N., Tobacco Warehouse |
| Munce, Thomas, House |
| Muncy Historic District |
| Municipal Building and Central Fire Station, 340 |
| Murray, Thomas, House |
| Nantmeal Village Historic District |
| Nathan's Department Store |
| National Bank of North Philadelphia |
| Nearpass House |
| Nebinger, George W., School |
| Neff, Maj. John, Homestead |
| Neff Round Barn |
| Nelson, John H., House |
| Nesbit-Walker Farm |
| Nesquehoning High School |
| New Baltimore Bridge |
| New Castle Hospital |
| New Century Clubhouse |
| New Colonial Hotel |
| New Enterprise Public School |
| New Era Building |
| New Freedom Railroad Station, Northern Central Railway |
| New Geneva Historic District |
| New Granada Theater |
| New Hamburg Historical Area |
| New Hope Village District |
| New Kensington Downtown Historic District |
| Newlin Mill Complex |
| Newlin Miller's House |
| Newmyer, Peter and Jonathan, Farm |
| Newport Historic District |
| New Ringgold Gristmill |
| New Thomson House |
| Newtown Friends Meetinghouse and Cemetery |
| Newtown Historic District |
| Newtown Presbyterian Church |
| Newville Historic District |
| New York Mutual Life Insurance Company Building |
| Nicholas, Jacob, House |
| Nichols, Jeremiah, School |
| Nicholson House and Inn |
| Nineteenth Street Theater |
| Nissly-Stauffer Tobacco Warehouses |
| Nissly Swiss Chocolate Company |
| Noble, J. L. School |
| Nook, The |
| Noon, Philip, House |
| Normandy Farmstead |
| Northampton County Bridge No. 15 |
| North Broad Street Mansion District |
| North Broad Street Station, Reading Company |
| Northbrook Historic District |
| North Charlotte Street Historic District |
| North East Historic District |
| Northeast Lancaster Township Historic District |
| Northeast Manual Training School |
| Northern Liberties Historic District |
| Northern National Bank |
| North Hill Historic District |
| North Prince Street Historic District |
| North Scranton Junior High School |
| Northumberland County Courthouse |
| Northumberland Historic District |
| North Wayne Historic District |
| Northwest York Historic District |
| Noxen School |
| N. Shippen-Tobacco Avenue Historic District |
| N. Snellenburg Company Department Store Warehouse |
| Nugent Home for Baptists |
| Nutt, Adam Clarke, Mansion |
| Nutting Hall |
| Nyce Farm |
| Oakdale Public School |
| Oak Hall Historic District |
| Oakland Public School |
| Oaklands |
| Oak Park Historic District |
| Oaks Cloister |
| O'Connor, J.S., American Rich Cut Glassware Factory |
Data from United States Park Service and Wikidata
