Altona is a town in Clinton County, New York, United States. The population was 2,887 at the 2010 census. The town was named after the Altona, Hamburg, district of Germany. The town contains a hamlet also called Altona.
The town is located in north-central Clinton County. The western part is inside the Adirondack Park boundary, but the entire town is specifically excluded from the park by statute. Altona is northwest of Plattsburgh.
The area was home to various cultures of indigenous peoples for thousands of years. Archeological studies have found that by 1300 CE, the St. Lawrence Iroquoians, a distinct group who spoke the Laurentian language, built fortified villages similar to those visited and described by explorer Jacques Cartier in the mid-16th century.