BNSF 6618 (ES44C4) enters the Denver Yard and heads to a train.

BNSF 1600 (SD40-2) works the yard in downtown Denver, Colorado.

Amtrak engine #18 (P42DC) backs through the BNSF yard as it heads to Denver's Union Station.

BNSF 1720 (SD40-2) works the yard in Denver, Colorado.

BNSF 9325 (SD70ACe) sits in the yard at the engine servicing facility waiting for an assigned train.

BNSF 6618 (ES44C4) moves into the Denver Yard and to a waiting train.

BNSF 1600 (SD40-2) works a cut of cars in the yard in downtown Denver, Colorado.

UP 1507 took an interesting route to its "North Yard Switcher" status. It was apparently built in April 1969 (so 55 years old in this picture) at Baltimore & Ohio GP40 #3738, then made i... (more)

It's 'Old School Day' at the engine servicing facility in Denver, Colorado as a AT&SF Bluebonnet and a Burlington Northern Cascade Green motor join the other motors.

A blackbird photo bombs Amtrak engine 151 as it leads the California Zephyr through the Denver Yard and to Denver's Union Station.

Light power huddle together at the BNSF engine servicing facility in Denver, Colorado.

BNSF 7213 (ES44DC) leads a stack train into the Denver Yard and will run east on the Brush Sub.

BNSF 1984 (SD40-2) works a cut of card in the Denver Yard with a former Burlington Northern Cascade Green motor.

Storm clouds move overhead as BNSF 8523 (SD70ACe) and other engines wait for servicing or assignments at the engine facility in downtown Denver, Colorado.

A golden sunrise glints off the Amtrak Winter Park Express Ski Train as it leaves Denver for the ski slopes in the Rocky Mountains.