- 2 Ovens (baking equipment)
- 38 Overbrook
- 14 Overbrook Avenue
- 11 Overbrook Park, Pennsylvania
- 6 Overbrook School for the Blind
- 17 Overhead views
- 12 Overington Street
- 1 Overlooks
- 2 Overproduction
- 14 Overs, John, 1808-1844
- 1 Oversewing machine
- 1 Ovid, 43 B.C.-17 A.D. or 18 A.D.
- 5 Owen, Richard, 1804-1892
- 1 Owen, Robert
- 34 Owls
- 1 Oxberry, William Henry, 1808-1852
- 38 Oxen
- 7 Oxford & Lower Dublin Poor House
- 6 Oxford Avenue
- 10 Oxford Circle, Pennsylvania
- 1 Oxford Iron & Steels Works-William & Harvey Rowland
- 1 Oxford Race Course
- 16 Oxford Street
- 1 Oxford Street Market
- 6 Oysters
- 6 P. & F. Corbin (Firm)
- 1 P. Brous & Co. (Firm)
- 1 P. Goumas & Co.
- 3 P. Ipsen (Firm)
- 1 P. Lenoir (Firm)
- 1 P.H. & F.M. Roots
- 4 P.H. Kelly Construction Company
- 1 P.H. Mayo & Bro.
- 1 P.N. Degerberg Tailor
- 3 Pacific Guano Company
- 7 Pacific Guano Company's Pavilion
- 1 Pacific Mills
- 1 Pacific Ocean
- 3 Packard
- 9 Packer Avenue
