UP 1837 (SD40N) sorts cars into the ladders at the Union Pacific's North Yard in Denver, Colorado.

UP 1980 (SD40N) works the local in Brighton on the Greeley Sub.

A SD40N (1598) repositions in the Union Pacific's North Yard in Denver, Colorado.

UP 1598 (SD40N) heads towards the services islands for fuel as a line of SD70Ms occupy the other track.

The yard is busy on this day as UP 1817 (SD40N) moves a cut of cars for sorting into the Union Pacific's North Yard in Denver, Colorado.

UP 1640 (SD40N) joins a variety of UP power at the servicing island in the North Yard.

UP 1359 GP40-2 works the intermodal facility in Denver, Colorado.

UP 1957 (SD40N) works the North Yard in Denver, Colorado.

UP 1826 (SD40N) works a cut of cars in the Union Pacific's North Yard in Denver, Colorado.

Fresh snow covers the North Yard in Denver, Colorado as UP 1826 (SD40N) works on sorting a cut of cars into the various ladders in the yard.

UP 1826 (SD40N) sits in the North Yard in Denver, Colorado waiting for the call to sort freight cars.

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

UP 1817 (SD40N) sits in the Union Pacific's North Yard in Denver, Colorado.

UP 1826 (SD40N) pulls up to the yard crew who will board as head to the north end of the yard.

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