On March 31, 1913, Stillwater County was officially created, becoming Montana's 34th county. The new county was carved out of parts of Carbon, Sweet Grass, and Yellowstone counties. The town of Columbus was designated as the county seat, and a gala celebration was held there to mark the occasion, despite challenging road conditions.

The formation of Stillwater County reflected the ongoing development and settlement of Montana, as increasing populations and economic activities, particularly in agriculture and mining, necessitated new administrative divisions. This event was a significant step in the political and geographical organization of the state, establishing local governance for a growing region and contributing to Montana.