Union City, Montana, human settlement in Madison County, Montana, United States of America

Union City is an abandoned settlement high in the mountains of Madison County, Montana, at about 7,580 feet (2,310 meters) in elevation. The site contained worker housing, storage sheds, and the remains of the Christenot Mill, which was equipped with Chilean rollers for crushing quartz.

Union City emerged in 1867 following the discovery of gold in nearby Alder Gulch in 1863. An investor named Christenot built a modern mill with imported machinery that began processing quartz and extracting gold in 1867.

Union City was a mining camp founded in 1867, named for the union of claims worked around the Christenot Mill. The site is now owned by the Bureau of Land Management and was listed on the National Register of Historic Places in 1999; no interpretive facilities or staff are present, so the remains of the camp are all that mark its past.

Union City sits at 7,582 feet (2,311 m) in Madison County, Montana, and the whole site is owned by the Bureau of Land Management. There is no visitor infrastructure, so plan for high-altitude weather and self-sufficient travel. The site was listed on the National Register of Historic Places in 1999.

The Christenot Mill used unusual Chilean roller technology instead of the stamping mills common at the time, making it innovative for its era. Equipment arrived in 52 ox-drawn wagons over the Bozeman Trail, a logistical feat that reflected the operation's ambitious scope.