UP 7798 (ES44AC) leads a tiple motor train through the North Yard in Denver, Colorado as it heads west.

UP 1019 (GP60) sits next to an old Chicago Northwestern sand car and will soon get the call to action to head into the North Yard in Denver, Colorado.

UP 688 (GP38-2) waits for the call to action to head into the North Yard in downtown Denver, Colorado to sort freight cars.

UP 3040, a Tier 4 SD70ACe, heads into the North Yard in Denver, Colorado and towards a waiting train.

A group of Union Pacific light power sits in the North Yard in Denver, Colorado.

UP 1825 (SD40N) crosses the Cherry Creek in downtown Denver, Colorado, on a bridge dating from the turn of the century.

UP 1825 (SD40N) works the North Yard in Denver, Colorado.

UP 1826 (SD40N) works the North Yard in Denver, Colorado.

It looks like UP 663 (GP38-2) has spent some time in California before moving to Denver, Colorado, where it works in the North Yard.

UP 3040 (SD70AH) runs with a mate into the North Yard and to a waiting train.

Tying Down at North Yard Union Pacific’s finest settles for the evening at Denver North Yard.

BNSF 8756 (SD70ACe) and partner engines get repositioned in the Denver Yard, heading for a waiting train. Notice the adjacent track where a grain hopper has dropped its entire load through the ya... (more)

A private owned New York Central Pullman car waits on the back of the California Zephyr at Denver's Union Station for a trip through the Colorado Rocky Mountains.

UP 688 (GP38-2) works a cut of cars deep in the North Yard in Denver, Colorado.

An old school Cascade Green SD40-2 works the yard in downtown Denver, Colorado.