Maryland - Significance region: National
| MARTHA LEWIS (skipjack) |
| Maryland Statehouse |
| MARY W.SOMERS (Chesapeake Bay skipjack) |
| McCollum, Elmer V., House |
| McKim's School |
| Mencken, H. L., House |
| MINNIE V |
| Monocacy National Battlefield |
| Montpelier |
| Mother Seton House |
| Mount Clare |
| Mount Royal Station |
| Mount Vernon Place Historic District |
| Moyaone Reserve Historic District |
| Myrtle Grove |
| MYSTERY (log canoe) |
| Naval Ordnance Laboratory |
| NELLIE CROCKETT |
| NELLIE L. BYRD |
| NIST Historic District |
| NODDY (log canoe) |
| Oakley, Annie, House |
| Ocean Hall |
| Old Lock Pump House, Chesapeake and Delaware Canal |
| Old National Pike Milestones |
| Old Roman Catholic Cathedral |
| OLIVER'S GIFT (log canoe) |
| One-Million-Liter Test Sphere |
| Paca House and Garden |
| Pascault Row |
| PATRICIA (log canoe) |
| Peale's Baltimore Museum |
| Peggy Stewart House |
| PERSISTENCE (log canoe) |
| Piney Point Coast Guard Light Station |
| Poe, Edgar Allan, House |
| Point of Rocks Railroad Station |
| Priest Neal's Mass House and Mill Site |
| Principio Furnace |
| RALPH T. WEBSTER |
| REBECCA T. RUARK |
| RELIANCE (Chesapeake Bay skipjack) |
| Remsen, Ira, House |
| Reward |
| Rigbie House |
| Rodgers Tavern |
| Roland Park Historic District |
| ROVER (log canoe) |
| Rowland, Henry August, House |
| RUBY G. FORD |
| SANDY (log canoe) |
| Sarum |
| Savage Mill Historic District |
| S. C. DOBSON (log canoe) |
| Scheifferstadt |
| SEA GULL |
| Seneca Quarry |
| Seton Hill Historic District |
| Shawnee Old Fields Village Site |
| Sheppard and Enoch Pratt Hospital and Gatehouse |
| Shot Tower |
| SIGSBEE |
| SILVER HEEL (log canoe) |
| Sion Hill |
| South River Club |
| Spacecraft Magnetic Test Facility |
| SS JOHN W. BROWN (Liberty Ship) |
| St. Alphonsus' Church, Rectory, Convent and Halle |
| STANLEY NORMAN |
| St. Catharine |
| St. Clement's Island Historic District |
| St. George's Parish Vestry House |
| St. Marys City Historic District |
| St. Mary's Seminary Chapel |
| St. Matthew's Church |
| Sumner, Charles, Post #25, Grand Army of the Republic |
| Surratt House |
| SUSAN MAY |
| Taylor, David W., Model Basin |
| TENNISON, WM. B. (Chesapeake Bay Bugeye) |
| Terra Rubra |
| Thomas Viaduct, Baltimore & Ohio Railroad |
| THOMAS W. CLYDE |
| Tome School for Boys Historic District |
| Tomlinson Inn and the Little Meadows |
| Tulip Hill |
| Turner's and Fox's Gaps Historic District |
| U-1105 BLACK Panther (Type VIIC German Submarine) |
| Union Mills Homestead Historic District |
| USCGC TANEY (WHEC-37) |
| U.S. Custom House |
| U.S. Naval Academy |
| U.S.S. CONSTELLATION |
| USS TORSK (submarine) |
| VIRGINIA W |
| Welch, William H., House |
| Westminster Presbyterian Church and Cemetery |
| West St. Mary's Manor |
| Whitehall |
| Wilson's Bridge |
Data from United States Park Service and Wikidata
