The Denver Zephyr continued operating after the Burlington Northern Railroad merger in 1970.

One pair was fully articulated 6-car trainsets used to replace the 3-car Twin Cities Zephyrs.

Accommodations on these trains included coaches, sections, single and double rooms, and dining and lounge facilities.

[5][6] On October 23, 1936, one of the new ten-car trainsets made a special run nonstop Chicago to Denver in an effort to break the 1934 record of the Pioneer Zephyr between the two cities.

[9][10][11] Distance was given as 1,017.22 miles (1,637.06 km) via Plattsmouth direct to Lincoln, Nebraska, bypassing Omaha on the regular route of the train.

[15] The trainsets were refurbished in the winter of 1948–49 and operated in DZ service until October 1956 when they were reassigned to the Denver–Fort Worth/Dallas Texas Zephyr route on Burlington subsidiaries Colorado and Southern and Fort Worth and Denver Railways.

But the train's consist — semi-articulated with a unique braking, steam connection system that was incompatible with other standard equipment — meant that cars could not be added to the train proper, but had to be added ahead of the baggage car or as a separate section.

Thus was conceived the last complete streamlined train to be built for a private railroad in the United States.

The new stainless steel train, also built by the Budd Company, offered all room sleeping accommodations and, in addition to a full diner, offered a Vista-dome coffee shop car called the Chuckwagon.

The pool required tight scheduling and good timekeeping and was discontinued when NP acquired eight additional slumbercoaches second-hand.

The Denver and Rio Grande Western Railway declined to join Amtrak, so the tri-weekly Union Pacific/Southern Pacific City of San Francisco was diverted from Cheyenne into Denver for combination with the Zephyr to Chicago.