- 8 Lehigh County, Pennsylvania
- 1 Lehigh Hosiery Co.
- 1 Lehigh Valley Railroad Co.
- 1 Lehigh, New York
- 7 Lehman (Firm)
- 1 Lehman, Frederick, Mrs.
- 1 Lehman, Peter, 1757-1823
- 9 Leicester Knitting Mills (Charles Spence & Co.) (Hosiery, knitted goods)
- 1 Leicester, England
- 1 Leinster, Augustus Frederick Fitzgerald, Duke of, 1791-1874
- 2 Leipzig, Germany
- 1 Leisenring, Luther Morris, 1875 - 1965, Architect
- 5 Leisure
- 3 Leithgow Street
- 2 LeMaistre, G.H.
- 2 Lemon Hill Drive
- 1 Lemon, Harry
- 69 Lemon, Mark, 1809-1870
- 2 Lemonade stands
- 12 Lenape, Pennsylvania
- 1 Lending
- 1 Lennig Chemical Works see Tacony Chemical Works
- 1 Lenoir & Forster
- 3 Lent
- 2 Lenz, David
- 3 Leo symbols
- 1 Leonard, Hubert Benjamin (Dutch), 1892–1952
- 5 Leopards
- 1 Leper colonies
- 1 Leprechauns
- 1 Leroy W. Fairchild & Co.
- 2 Lesage & Paignard
- 1 Leslie, Charles Robert, 1794-1859
- 1 Leslie, Malachi (Max) G., 1864-1933
- 1 Letter carriers
- 2 Letter carriers
- 1 Letter openers
- 1 Lettering
- 14 Letterpress printing
- 96 Letters (correspondence)
