Northern Pacific 50-foot, single plug door, refrigerator car 97053 is in a train at Broomfield, Colorado, on March 5, 1975. The car is part of the 97000-97099 number series. Photo by GJ Werkema. Other subject classes: freight car, refrigerator car

Northern Pacific 50-foot, single plug door, refrigerator car 97090 is in a yard at Albuquerque, New Mexico, on August 5, 1979. The car is part of the 97000-97099 number series. Photo by GJ Werkema. Other subject classes: freight car, refrigerator car

Northern Pacific 50-foot, single plug door, refrigerator car 97552 is in a yard at Albuquerque, New Mexico, on May 30, 1980. The car is part of the 97500-97549 number series. Photo by GJ Werkema. Other subject classes: freight car, refrigerator car

Northern Pacific 50-foot, single plug door, refrigerator car 97629 is in a yard at Albuquerque, New Mexico, on February 19, 1979. The car is part of the 97600-97692 number series. Photo by GJ Werkema. Other subject classes: freight car, refrigerator car

Northern Pacific 50-foot, single plug door, refrigerator car 97638 is in a yard at Albuquerque, New Mexico, on December 20, 1978. The car is part of the 97600-97692 number series. Photo by GJ Werkema. Other subject classes: freight car, refrigerator car

Northern Pacific 50-foot, single plug door, refrigerator car 97638 is in a train at Albuquerque, New Mexico, on August 15, 1990. The car is part of the 97600-97692 number series. Photo by GJ Werkema. Other subject classes: freight car, refrigerator car

Northern Pacific 50-foot, single plug door, refrigerator car 97642 is in a yard at Albuquerque, New Mexico, on September 29, 1980. The car is part of the 97600-97692 number series. Photo by GJ Werkema. Other subject classes: freight car, refrigerator car

Northern Pacific 50-foot, single plug door, refrigerator car 97727 is in a train at Belen, New Mexico, on May 22, 1994. The car is part of the 97700-97799 number series. Photo by Evan Werkema. Other subject classes: freight car, refrigerator car

Northern Pacific 50-foot, single plug door, refrigerator car 97745 is on a siding at Cle Elum, Washington, on April 1, 1987. The car is part of the 97700-97799 number series. Photo by GJ Werkema. Other subject classes: freight car, refrigerator car

Northern Pacific 50-foot, single plug door, refrigerator car 97798 is on a siding at Enid, Oklahoma, on May 19, 1995. The car is part of the 97700-97799 number series. Photo by GJ Werkema. Other subject classes: freight car, refrigerator car