- People's Publishing Company.2
- Pettibone, Darwin A., 1827-18942
- Pharus-Verlag.2
- Picquet, Charles, 1771-1827.2
- Poirson, J. B. (Jean Baptiste), 1760-18312
- Port Authority Trans-Hudson Corporation2
- Portillo, Pedro2
- Powell, Richard L., cartographer.2
- Pownall, Thomas, 1722-18052
- Québec (Province). Département des terres de la couronne2
- Quinn, E. J. (Edward J.)2
- R.W. Johnson & Son (Firm : Saint Paul, Minn.)2
- Railroad Commission of Washington2
- Rand Avery Supply Co2
- Real Estate Title and Trust Co. (Portland, Or.)2
- Reckless, Walter C., 1899-19882
- Renshawe, John H.2
- Reuben H. Donnelley Corporation2
- Reynolds, James, active 1845-1864.2
- Rinker, Andrew2