Named for the many large boulders in the vicinity, the town of Boulder Valley was established in the early 1860s as a stagecoach station on the route between Fort Benton and Virginia City.[5] It later became a trading center for nearby agricultural areas and the Elkhorn, Comet, and Baltimore mining districts. The Great Northern Railway branch line from Helena to Butte reached Boulder in 1888. State schools for the deaf, blind, and developmentally disabled were established in the city in 1892. In 1897, the town's name was shortened to Boulder.[6]

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