Henderson is a town in Jefferson County, New York, United States. The population was 1,360 at the 2010 census. The town is named after William Henderson, the original European-American land owner.

Jefferson County is a county on the northern border of the U.S. state of New York. As of the 2020 census, the population was 116,721. Its county seat is Watertown. The county is named after Thomas Jefferson, third President of the United States of America. It is adjacent to Lake Ontario, southeast from the Canada–US border of Ontario. The county is part of the North Country region of the state.