As the U.S. highway and freeway system grew, often paralleling railroad tracks, not all was ideal for the Southern Pacific. Passenger revenues faded from the end of the second world war into the 1960s. In 1971, along with the majority of U.S. railroads, the SP gave up intercity passenger trains to the newly formed National Railroad Passenger Corporation, more commonly known as AMTRAK. The SP operated several long distrace trains for AMTRAK and kept its community line between San Francisco and San Jose, California.

Railroad operations not lost passengers but freeways opened up the world of intercity trucking, and gaining revenue and new contracts meant offering long distance train service at highly competitive rates. The Southern Pacific Transportation Company attempted to create a merger with the Atchison, Topeka and Santa Fe Railroad in 1983, but the Interstate Commerce Commission rejected the proposed merger in 1987, and the Southern Pacific was sold to Rio Grande Industries, the operator of the Denver and Rio Grande Western Railroad one year later with the intention of the SP herald being the surviving brand. It wasn’t to be, as in 1996, the merged SP/D&RGW was sold and incorporated into the Union Pacific Corporation. Overall, these rail lines, collectively called the Union Pacific Transportation Company became the largest railroad company in the United States and controlled nearly all rail-based shipping in the western two-thirds of the United States.