- Orangeburg Bar1
- Oratorio Society of New York1
- Orcutt, L., 1830-1
- Orr, J. L. (James Lawrence), 1822-18731
- Orshansky, Mollie1
- Osborn, Alex F. (Alex Faickney)1
- Ott, Oliver Frank, 1866-19391
- Paderewski Birthday Celebration1
- Paderewski Foundation1
- Palmer, B. M. (Benjamin Morgan), 1818-19021
- Palmer, Benjamin M. (Benjamin Morgan), 1781-18471
- Pappastavrou, George1
- Parke, Davis & Co.1
- Parker & Lee1
- Pelham, W.C.1
- Pemberton, A. H.1
- Peoples' Steam Ship Company of So. Ca.1
- Pepoon, Benjemin F.1
- Peronneau, Henry William (Chairman Standing Committee Charleston State Rights Associatio1
- Perry, Benjamin Franklin, fl. 18901