On August 30, 1991, the eastbound Burlington Northern Railroad (BN) freight train 602 departed Shelby, Montana, heading south. Westbound BN freight train 603 departed Great Falls, Montana, proceeding north. Both trains were routed over BN unsignaled single track line between Shelby and Great Falls. A branch line dispatcher in Seattle, Washington, controlled the trains' movements by issuing track warrants through a computerized track warrant control system.
At 5:50 p.m. mountain daylight time at milepost 85.55 north of Ledger, Montana, the two trains collided head on at a closing speed of 87 mph. After impact, fire ensued from spilled locomotive diesel fuel, burning locomotive units, two freight cars, and grass. Nine locomotive units and 22 cars were destroyed; 9 cars were damaged. Track damage, equipment replacement, and clean-up costs were estimated at $19 million. Three crewmen were killed, and four were severely injured.