Most of the mines associated with the bankrupt Rocky Mountain Fuel Co., including the Columbine, were closed in 1946, after which area mines were owned and run by independent owners. Lafayette's last mine, the Black Diamond, located at today's U.S. 287 and Baseline Road, closed in 1956. The independently owned Hi-Way mine in Louisville and the Gorham in Superior closed in 1955. Erie's Eagle mine was the last coal mine to operate in the Northern Coal Field. It closed in 1975.