Jefferson is a town in Coos County, New Hampshire, United States. The population was 1,043 at the 2020 census. It is home to parts of the White Mountain National Forest in the south and northeast and to Santa's Village, a Christmas-themed amusement park. There are also several private campgrounds, motels and inns.

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.