Pennsylvania - Area of significance: Industry
| Hayes Mill House |
| Hazelwood Brewing Company |
| Heinz, H.J., Company |
| Heishman Mill |
| Heiss, William A., House and Buggy Shop |
| Helfrich's Springs Grist Mill |
| Hendel Brothers, Sons and Company Hat Factory |
| Henry Whitaker’s Sons’ Mill |
| Herpel Brothers Foundry and Machine Shop |
| Hershey, Milton S., Mansion |
| Heywood Chair Factory |
| Hill's Sawmill |
| Hockley Mill Farm |
| Hokendauqua Thomas Iron Company Town Historic District |
| Holicong Village Historic District |
| Hollidaysburg Historic District |
| Holman, A. J., and Company |
| Hopewell Furnace National Historic Site |
| Hopewell Historic District |
| House at Upper Laurel Iron Works |
| House of Miller at Millbach |
| Howell and Brothers Paper Hangings Manufactory |
| Hoyle, Harrison & Kaye Textile Mill |
| Hudson Grist Mill |
| Hulmeville Historic District |
| Hunter Saw & Machine Company |
| Hunter's Mill Complex |
| Huntingdon Furnace |
| Illick's Mill |
| Irish-Townsend House |
| Irwinton Historic District |
| Irwintown Site |
| Isabella Furnace |
| Ivy Mills Historic District |
| Jacobsburg Historic District |
| Joanna Furnace Complex |
| Johnsonburg Commercial Historic District |
| Johnson, Nicholas, Mill |
| Jones, Benjamin F., Cottage |
| Juniata Iron Works |
| Juniata Woolen Mill and Newry Manor |
| Kauffman Mill |
| Keefe-Mumbower Mill |
| Kenderdine Mill Complex |
| Kennett Square Historic District |
| Keystone Mill |
| Kidd's Mills Covered Bridge Historic District |
| Kise Mill Bridge Historic District |
| Kitson Woolen Mill |
| Knabb-Bieber Mill |
| Kreider Shoe Manufacturing Company |
| Kuster Mill |
| Kutz Mill |
| Kutztown Silk Mill |
| Lackawanna County Courthouse and John Mitchell Monument |
| Lackawanna Iron and Coal Company Furnace |
| Lackawanna Mills and Scranton Button Historic District |
| Lancaster City Historic District |
| Lancaster Watch Company |
| Landis Homestead |
| Landis Shoe Company Building |
| Lansdale Silk Hosiery Company-Interstate Hosiery Mills, Inc. |
| Lansford Historic District |
| Larkin-Belber Building |
| Laurel Hill Furnace |
| Lawrenceville Historic District |
| Lee Tire and Rubber Company |
| Lehigh Canal |
| Lehigh Canal; Allentown to Hopeville Section |
| Lehigh Canal: Eastern Section Glendon and Abbott Street Industrial Sites |
| Lehigh Valley Railroad Headquarters Building |
| Lehigh Valley Silk Mills |
| Lehner Grain-and-Cider Mill and House |
| Lightfoot Mill |
| Linden House |
| Little Buffalo Historic District |
| Lock Ridge Furnance Complex |
| Logan Mills Gristmill |
| Logans Ferry Powder Works Historic District |
| Long-Hawerter Mill |
| Lovell Manufacturing Company |
| Lukens Historic District |
| Lumberville Historic District |
| Lupfer, Israel and Samuel, Tannery Site and House |
| Lycoming Rubber Company |
| Manayunk Main Street Historic District |
| Manheim Borough Historic District |
| Mansfield |
| Marianna Historic District |
| Marietta Historic District |
| Martin, B. B., Tobacco Warehouse |
| Martin, C.F. & Company. |
| Mary Ann Furnace Historic District |
| Mascot Roller Mills |
| Mauch Chunk and Summit Hill Switchback Railroad |
| McCollum and Post Silk Mill |
| McCormick, John B., House |
| McGovern, Edward, Tobacco Warehouse |
| Meadville Downtown Historic District |
| Meason, Isaac, House |
Data from United States Park Service and Wikidata
