 GEOG: Early in this episode, a freight train is seen leaving  Wilmington, Delaware, hauled by Southern Pacific diesel locomotives;  the Southern Pacific didnt operate east of the Mississippi River.  Later, the train is seen traveling through the mountains of  Pennsylvania hauled by Denver & Rio Grande Western ("Rio Grande")  diesels; the Rio Grande operated only in Colorado, Utah, and (at one  time) New Mexico. While these apparent mismatches are probably due  to the use of stock footage, they are not necessarily errors. By the  late 1960s, American railroads were routinely leasing diesels to  each other, combining their locomotive fleets into jointly used  pools, and operating "run through" trains that remained intact from  origin to destination over more than one railroad. Through such  practices, diesel locomotives could 