Hillsboro is a small unincorporated community in Sierra County, New Mexico, United States, located in the southwestern part of the state. It was founded in 1877, following the discovery of gold. The community was the county seat of Sierra County from 1884 until 1936 when Hot Springs became the county seat. Between 1893 and 1898, 100,000 troy ounces (3,000 kg) of gold were produced there. About 1986, the film Lewis & Clark & George was filmed in the vicinity.