Altmar is a hamlet (and census-designated place) in Oswego County, New York, United States.

On November 10, 2010, residents of Altmar voted to dissolve their village's government under Governor Andrew Cuomo's Government Reorganization and Citizen Empowerment Act, becoming the first village to do so under the act; the margin was a mere six votes.

[8] The village was dissolved on June 1, 2013[9] and remains an area within the Town of Albion.

Located within Altmar is the Salmon River Fish Hatchery, operated by the New York State Department of Environmental Conservation to support the state's stocking program for Lake Ontario and Lake Erie.

20.2% of all households were made up of individuals, and 7.6% had someone living alone who was 65 years of age or older.

This climatic region is typified by large seasonal temperature differences, with warm to hot (and often humid) summers and cold (sometimes severely cold) winters.