oats [3 subentries]

O'Brian (O'Brien), Capt. [See redirect]

O'Bryen (O'Brian, O'Brien), Richard [4 subentries]

Observations on the Whale-Fishery [1 subentry]

Occoquan Mills, Va. [1 reference]

Official Letters to the Honorable American Congress (John Carey) [1 subentry]

Ogden, Mr. [1 subentry]

Ohio Company [1 reference]

Ohio river [1 subentry]

oil [3 subentries]

Old Telassee [1 reference]

Old Will (TJ's slave) [1 subentry]

olive culture [2 subentries]

Oliver, William (master of Sion) [3 references]

Oliver Cromwell (ship) [1 reference]

Olivier, Pedro [2 subentries]

Omar Ben Dandi [1 subentry]

O'Neal, William [1 subentry]

O'Neill, Arturo [1 subentry]

Ontario Co., N.Y. [1 subentry]

Opinions on Interesting Subjects (George Chalmers) [1 subentry]

Oraczewski, Felix, Comte d' [1 subentry]

Orange, Prince of [See redirect]

Orange, Princess of [See redirect]

Orange Co., N.C. [1 subentry]

Orange Co., N.Y. [1 subentry]

Orange Co., Va. [1 subentry]

Ore, James [1 subentry]

Orléans, Louis Philippe Joseph, Duc d' [3 subentries]

Ormsby, John [1 subentry]

orrery [1 subentry]

Orvilliers, Louis Guillouet, Comte d' [1 reference]

Osgood, Samuel [1 subentry]

Ostego Co., N.Y. [1 subentry]

Oster, Martin [1 subentry]

Oswego, N.Y. [1 subentry]

Otis, Harrison Gray [1 subentry]

Otis, Samuel A. [1 subentry]

Otto, Louis Guillaume [1 subentry]

outfit, diplomatic [2 subentries]

Outlines of the Doctrines in Natural History, Chemistry, and Economics (Samuel Latham Mitchill) [1 subentry]

Owen, David [1 subentry]