Columbia is a town in Coös County, New Hampshire, United States. The population was 659 at the 2020 census, down from 757 at the 2010 census. It is part of the Berlin, NH-VT micropolitan statistical area.

Coös County or Coos County is a county in the U.S. state of New Hampshire. As of the 2020 census, the population was 31,268, making it the least-populated county in the state. The county seat is Lancaster.