The Henderson Mine is located 50 miles west of Denver, CO. The mine has been in operation since 1976 using a panel caving process and a rail transportation system to mine molydbenum. The rail system was a 42-inch cantenary style railroad. Motive power was supplied by 32 Swedish built ASEA electric locomotives. Each locomotive rode on two axles and weighed 55 tons and was dual voltage 1400 and 600 d.c. volts. The lower voltage was for safety purposes in close clearance portions of the mine. The Henderson Mine also had three small diesels on their roster for non-electrified portions of the line. The rail line moved ore 14 miles from the mine to the mill using 250 20 ton ore cars. The railroad included a 9.8 mile tunnel under the Continental Divide that was longer than either the Cascade or Moffat tunnels. The tunnel was said to be the 10th longest railroad tunnel in the world. After 23 years of operation the railroad ceased operation on July 30, 1999. This unique railroad was replaced by a conveyor belt system and an historic piece of Colorado mining history became a memory.