The crew of UP 1865 (long snoot SD40N) calls it a day after working the yard in LaSalle, Colorado.

There is a mix of heavy and light power in the Union Pacific's North Yard in Denver, Colorado.

The sun has just risen as UP 845 (GP38-2) works a cut of cars into the ladder in the Union Pacific's North Yard in Denver, Colorado.

Snow from the previous day's storm blankets the ground as the California Zephyr runs past a ranch in Coal Creek Canyon, Colorado.

The California Zephyr climbs out of Coal Creek Canyon, Colorado towards Tunnel #1 on the Moffat Tunnel Sub.

A weathered BNSF 2028 (GP38-2) waits at the depot in Longmont, Colorado.

BNSF 9225 (SD70ACe) runs between the refineries in Commerce City, Colorado as it heads to Denver.

The California Zephyr runs through Tunnel #3 on the Moffat Tunnel Sub as it begins the climb into the Colorado Rocky Mountains.

UP 1817 (SD40N) and other light power sit in an echelon right formation in the Union Pacific's North Yard in Denver, Colorado.

Old signal poles still line the tracks as UP 4363 (SD70M) brings a freight into Platteville, Colorado.

UP 1980 (GP38N) joins other light power in the North Yard as they wait for their chance to sort freight cars.

UP 1502 (GP40M) works the North Yard in Denver Colorado.

The California Zephyr runs through Little Ten Curve at Rocky Colorado and begins the journey to the Moffat Tunnel.

UP 7689 (ES44AC) runs to the service islands with a Canadian Pacific Unit at the UP's North Yard.

UP 845 (GP38-2) has just released a cut of cars into the Union Pacific's North Yard in Denver, Colorado.