A birds eye view of the largest yard in the world - UP Baily Yard.

Yard power for Laramie Yard sits on a quiet Wyoming morning.

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

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

UP 1957 (SD40N) brings a short cut of cars through the refineries in Commerce City, Colorado.

UP 1905 (SD40N) heads into the North Yard in Denver, Colorado for a stint of shuffling freight cars.

UP 1640 (SD40N) waits in the Union Pacific's North Yard in Denver, Colorado for orders to sort cars.

A variety of light and heavy power wait for servicing at the North Yard in Denver, Colorado.

UP 1865 (SD40N) leads the local through Greeley, Colorado.

UP 1640 (SD40N) works the North Yard in Denver, Colorado.

UP 1947 leads a trio of SD40N's south over the Mississippi River. The 1913 built CGW lift bridge is still holding strong to this day but is scheduled to be replaced.

UP SD40N 1950 leads YPRCN East through LaGrange Park.

UP 1826 (SD40N) runs solo into the North Yard in Denver, Colorado.

A set of UP motors runs through the North Yard in Denver, Colorado.

With only seconds of sunlight left, UP 1997 (SD40N) leads the local through Greeley, Colorado on its way back to LaSalle.