Eureka is a town in Lincoln County, Montana, United States, 9 miles (14 km) south of the Canada–US border. The population was 1,037 at the 2010 census. The town's mayor is LeeAnn Schermerhorn.
Eureka is located at 48°52′49″N 115°2′58″W (48.880265, −115.049325), approximately 66 miles (106 km) from Kalispell.
According to the United States Census Bureau, the town has a total area of 1.01 square miles (2.62 km2), all of it land.
The Town of Eureka is located on the Tobacco River in an area known as the Tobacco Valley in the United States and as the Tobacco Plains in British Columbia to the north. Eureka was founded in the early 1880s as settlers moved north from Missoula and south from Canada and was originally known as Deweyville. It was one of the last areas to be developed in Montana in frontier times, and logging was a major draw and source of income for decades. Eureka was once known as the "Christmas Tree Capital of the World," with evergreens shipped to many urban points for holiday sales.
The Canadian fur-trapper and explorer David Thompson visited the area in the early 19th Century during his searches for a route to the Pacific Ocean. Early explorers, finding Indians there growing a native strain of tobacco, named it the Tobacco Plains.