Northern Pacific 50-foot, box car number 6042 with double-doors is in a train at Denver, Colorado, on March 19, 1982. The car is part of the 6000-6499 number series. Photo by GJ Werkema. Other subject classes: freight car, steel box car

Northern Pacific 40.75-foot, box car number 42284 with a sliding door is in a train at Denver, Colorado, on February 25, 1976. The car is part of the 42115-42989 number series. Photo by GJ Werkema. Other subject classes: freight car, steel box car

Northern Pacific 50-foot, wagon-top, double sliding door box car 39626 is spotted at a loading ramp at the Denver Union Terminal facility on September 3, 1967. The leased car is part of the 39626-39759 number series. Photo by GJ Werkema. Other subject classes: freight car, steel box car

Northern Pacific box car 2821 in a train in Denver, Colorado, on March 19, 1982. Box car NP 2821 was built by the NP Car Shops in Brainerd, Minnesota, in 1963 as part of the 50-foot, double-door box car series numbered from 2350-2849. Photo by GJ Werkema. Other subject classes: freight car, steel box car

Northern Pacific 40.5-foot, wood, war emergency box car number 28014 with one sliding door is in a yard at Denver, Colorado, on June 1, 1970. The car is part of the 28000-28749 number series. Photo by GJ Werkema. Other subject classes: freight car, wood box car

Northern Pacific 40.5-foot, wood, war emergency box car number 28110 with one sliding door is on a repair track at Denver, Colorado, on June 1, 1970. The car is part of the 28000-28749 number series. Photo by GJ Werkema. Other subject classes: freight car, wood box car

Northern Pacific 40.5-foot, wood, war emergency box car number 28317 with one sliding door is in a train at Denver, Colorado, on June 10, 1967. The car is part of the 28000-28749 number series. Photo by GJ Werkema. Other subject classes: freight car, wood box car

Northern Pacific 40.75-foot, box car number 27316 with one sliding door is on a siding at Denver, Colorado, on January 26, 1982. The car is part of the 26000-27349 number series. Photo by GJ Werkema. Other subject classes: freight car, steel box car

Northern Pacific box car 1853 in a train in Denver, Colorado, on May 10, 1978. Box car NP 1853 was built by the NP Car Shops in Brainerd, Minnesota, over 1967-69 as part of the 50-foot, plug door box car series numbered from 1700 to 1999. Photo by GJ Werkema. Other subject classes: freight car, steel box car

Northern Pacific 40.75-foot, box car number 15529 with one sliding door is in a yard at Denver, Colorado, on April 10, 1965. The car is part of the 15500-15999 number series. Photo by GJ Werkema. Other subject classes: freight car, steel box car