Oriskany Public Library

New York.

Orland Park Public Library

Illinois.

Orono Public Library

Maine.

Orr's Island Library

Maine.

Orrville Public Library

Orrville, Ohio.

Országos Széchényi Könyvtár / National Széchényi Library

The National Libary of Hungary.

Osage County Library

Linn, Missouri.

Oscoda County Library

Mio, Michigan.

Osgood Public Library

Osgood, Indiana. Serving Center, Delaware, Franklin and Washington Townships.

Oshawa Military and Industrial Museum

Ontario.

Oshkosh Public Library

Oshkosh, Wisconsin.

Oshkosh Public Library Digital Collections

Postcards, city directories, atlases, local history books, rural schools and businesses.

Ossining Public Library

New York.

Oswayo Valley Memorial Library

Shinglehouse, Pennsylvania.

Oswego County Clerk - Records Center Research Materials

Oswego, New York.

Oswego School District Public Library

New York.

Otsego County Library

Gaylord, Michigan.

Otsego District.

Michigan.

Ottawa County Historical Museum

Minneapolis, Kansas.

Ottawa House By-The-Sea Museum

Home of the Parrsborough Shore Historical Society, Parrsboro, Nova Scotia, Canada.