A drove of Burlington Northern E-units wait their next call to duty in Aurora, Illinois in October, 1985. These warriors were rebuilt by Morrison-Knudsen, and were fixtures on BN's Racetrack until 1992.
There are times when many engines, cars or cabooses are concentrated in a location. Such sites are for storage, economic reasons, active power needs or for rebuilding. For others, wear and tear have brought their usefulness to and end.