WCHS was founded in 1874 as a member-based, not-for-profit agency incorporated by the State of New York to serve the citizens of Westchester County. Named as the official County Historian in 2006, the Society's mission is to collect and preserve books, pamphlets, maps, manuscripts, photographs, newspapers, periodicals, film, video and digital materials pertaining to the history of Westchester County, to promote the knowledge and understanding of that history, and to advocate for the preservation of the county's architectural heritage.