 Because of the strength and importance of its research collection, the Boston Public Library is a member of the Association of Research Libraries (ARL), a not-for-profit organization comprising the research libraries of North America.The New York Public Library is the only other public library that is a member of the ARL, and it also has a private endowment.The library has established collections of distinction, based on the collection's depth and breadth, including such subjects as Boston history, the Civil War, and Irish history.