Maryland - Criteria: C (architecture/engineering)
| Harper, George, Store |
| Harrington |
| Harris Farm |
| Harris, Nathan and Susannah, House |
| Haviland, Edward W., House |
| Havre de Grace Historic District |
| Hawkins Pharsalia |
| Hayman, Jeptha, House |
| Hays-Heighe House |
| Hays House |
| Hays, Joseph C., House |
| Hayward's Lott |
| Hazelwood |
| Hebrew Orphan Asylum |
| Hebron |
| Heighe House |
| Heiser, Rosenfeld, and Strauss Buildings |
| HELIANTHUS III (yacht) |
| Henry's Grove |
| Hermitage, The |
| Hessian Barracks |
| Hidden Valley Farm |
| Highbarger, Jacob, House |
| Highfield House |
| Highland Lodge |
| HILDA M. WILLING |
| Hilleary, William, House |
| Hill House |
| Hills, Dales, and the Vineyard |
| Hilltop Manor |
| Hilton |
| Hinchingham |
| Hippodrome Theatre |
| His Lordship's Kindness |
| Hitt's Mill and Houses |
| Hobson's Choice |
| Hochschild, Kohn Belvedere and Hess Shoes |
| Hocking House |
| Hoffman Farm |
| Hoffman, Isaac, House |
| Hogmire-Berryman Farm |
| Hollins-Roundhouse Historic District |
| Holly Hall |
| Holly Hill |
| Homewood |
| Honeysuckle Lodge |
| Hood College Historic District |
| Hooper Island Light Station |
| Hooper, James E., House |
| Hopeful Unity |
| Hope House |
| Hopewell |
| Hopewell |
| Hotel Kernan |
| House at 9 North Front Street |
| "House by the ""Town Gates""" |
| Houses At 16-22 East Lee Street |
| Howard Lodge |
| Howard Park P.S. 218 |
| Howard's Inheritance |
| Howard Street Tunnel |
| Huckleberry Hall |
| Hughes A.M.E. Chapel |
| Hutzler Brothers Palace Building |
| Hyattsville Armory |
| Iglehart |
| Indian Queen Tavern and Black's Store |
| Indian Range |
| Industrial Building |
| Ingram-Schipper Farm |
| ISLAND BIRD (log canoe) |
| ISLAND IMAGE (log canoe) |
| ISLAND LARK (log canoe) |
| Ivory Mills |
| Jackson, Sen. William P., House |
| JAY DEE (log canoe) |
| Jena |
| Jericho Covered Bridge |
| Jericho Farm |
| Jerusalem Mill Village |
| Johns Hopkins Hospital Complex |
| Johnsontown Tobacco Barn No. 2 |
| Johnson-Wolfe Farm |
| Johnston Building |
| Joshua's Meadows |
| Kaese Mill |
| Keating House |
| Keedy House |
| Keedysville Historic District |
| Keefer-Brubaker Farm |
| Kefauver Place |
| Kennersley |
| Kensington Historic District |
| Kernan, James Lawrence, Hospital |
| Kingston |
| Kingston Hall |
| Kirk, Elisha, House |
| Kitterman-Buckey Farm |
| Klots Throwing Company Mill |
| Knipp, George, & Brother Building |
Data from United States Park Service and Wikidata
