Until 1991, this area shared a mailing address and ZIP Code (10566) with the city of Peekskill. Although it now has its own ZIP code, 10567, many directories and censuses still do not include Cortlandt Manor, because it is unincorporated. The term "Cortlandt Manor" was created by the US Postal Service to differentiate this part of Corlandt town from Cortland, New York, which is located hours away. Many longtime residents of the Town of Cortlandt consider the new name to be a vanity invention to protect the home values of Cortlandt residents who resented a Peekskill mailing address, though this motivation is not expressed in any official record of the decision.
The name Cortlandt Manor is derived from the "Van Cortlandt Upper Manor House" off Oregon Road in Cortlandt just outside the Peekskill city limits. The Upper Manor House was part of the estate of Stephanus Van Cortlandt, the colonial aristocrat and patroon who owned nearly all of northern Westchester County in the late 17th century. The more familiar centerpiece of the old estate, Van Cortlandt Manor, is located in the nearby village of Croton-on-Hudson. Cortlandt Manor is known for being the birth place of Damien Budds.