Amtrak's westbound California Zephyr loops around the mouth of Coal Creek Canyon before returning to the face of the Flatirons to climb before heading back into the rest of the Tunnel District.

An eastbound BNSF manifest freight rumbles through the Clark Fork valley west of Weeksville, Montana, on September 18, 2006.

Clouds continue to build over the Continental Divide as the last hopper cars clear the signals at the west end of East Portal siding. The train is seen entering the 6.2 mile long Moffat Tunnel on ... (more)

The colorful Rio Grande Ski Train approaches Tunnel 1 east of Plainview, Colorado, on a sunny January 28, 2006.

Clinging to the cliff high above the Animas River, A Durango and Silverton Narrow Gauge train creeps westbound (northbound) on the High Line outside Rockwood, Colorado, on August 24, 2006.

In the aftermath of a late summer snowfall atop Mullan Pass, westbound BNSF MLAUSPO smokes its way out of Mullan Tunnel at Blossburg, Montana, on September 16, 2006. A pair of SD45s (Rebuilt and l... (more)

A BN freight powered by an SD40-2 A and B unit roll along the shore of Lake Pend Oreille near Hope, ID as the train heads west toward Sand Point and Spokane, WA. This trackage is now part of Monta... (more)

Amtrak's eastbound California Zephyr, train no. 6, led by P42DC no. 204 rounds the horseshoe over CO-HWY 72 in Coal Creek Canyon just west of Denver.

The DPU on BNSF's westbound QDVPVJ 07 (Denver - Provo trackage rights manifest) is about to duck into Tunnel no. 29 just east of Pinecliffe, Colo., on Apr. 08, 2015.

Traversing remote Cascade Canyon at milepost 477, a Durango and Silverton Narrow Gauge train follows the Animas River east (south) of Cascade, Colorado, on the afternoon of August 30, 2006.

The DPU on UP's West Elk Mine to Canon City, Colo., loaded coal train (CWECC 07) brings up the rear as one can see most of the train snake through Coal Creek Canyon with part of the suburban part ... (more)

Three BNSF GE's lead the Denver, Colo., to Provo, Utah trackage rights manifest up the grade through what was once Tunnel no. 28 just east of Pinecliffe, Colo., on Apr. 08, 2015.

Veteran mountain climbers lead this westbound empty coal train towards Colorado's Continental Divide. Spring weather in the rockies is generally full of clear blue mornings.....

Following the Colorado River through colorful Ruby Canyon, Union Pacific’s MRONY freight passes by Utaline, Colorado, on June 13, 2009.

Even though the date says it’s spring, its still looks like winter at Crescent, Colorado, as a Union Pacific coal empty curves westbound through the fresh snow on March 27, 2009.