A bison walks in the Rocky Mountain Arsenal National Wildlife Refuge, with the Denver skyline visible in the background. This image took second place in the 2017 RMANWR photo contest. #

A Durango & Silverton Narrow Gauge Railroad train proceeds along the rocky "Highline" ridge high above the Animas River Valley in La Plata County, Colorado, on June 1, 2015. The D&SNG is a narrow-gauge railroad that operates 45.2 miles of track between Durango and Silverton in southwest Colorado. The route was originally opened in 1882 by the Denver & Rio Grande Railway to transport silver and gold ore mined from the San Juan Mountains. The line has run continuously since 1881, and some rolling stock dates to then. It is now strictly a tourist and heritage line hauling passengers and is one of the few places in the United States that has seen continuous use of steam locomotives. #

A young mountain goat leaps across rocks on Mount Evans. The peak of the 14,271-foot mountain is reachable by car, along the Mount Evans Scenic Byway—the highest paved road in North America. #

Crystal Mill, a powerhouse built in 1892 for nearby silver-mining operations, above the Crystal River in Gunnison County, Colorado. The building used water power to create compressed air that was then used to power other machinery. #

A bobcat walks through the Pueblo Chemical Depot, a chemical-weapons storage site east of Pueblo, Colorado. The site is a 23,000-acre military installation located in the shortgrass prairie. Natural and cultural resources there are managed by U.S. Fish and Wildlife Service personnel. #

Jeff Dahl races down Harrison Avenue while the skier Jason Dahl airs out off the final jump of the Leadville skijoring course during the 71st annual Leadville Ski Joring weekend competition on March 3, 2019, in Leadville, Colorado. Skijoring, which has its origins as a competitive sport in Scandinavia, has been adapted over the years to include jumps, slalom gates, and spearing rings for points. Leadville has been hosting skijoring competitions since 1949. #

A Pikes Peak Cog Railway car travels down from the summit of Pikes Peak. The railway runs from nearby Manitou Springs to the mountaintop along steep rails, in some places reaching a grade of 24 percent. The railway is currently closed while undergoing major renovations, and plans to reopen in 2021. #

A scene on a day when heavy snow covered the main street of Telluride, Colorado, on January 31, 2016. Telluride, the most populous town in San Miguel County, began as a silver-mining camp on the San Miguel River. #

The Cliff Palace, in Mesa Verde National Park. The park is home to nearly 5,000 known archaeological sites related to the Ancestral Pueblo people who lived and built homes here between the seventh and 13th centuries. #

Leadville's historic 650-seat Tabor Opera House was built in 1879, and once held performances by Oscar Wilde, John Philip Sousa, and Buffalo Bill, among others. The structure was purchased by the city of Leadville in 2016, and rehabilitation efforts are under way. #

Longhorn steers lead the National Western Stock Show kickoff parade up 17th Avenue in Denver, Colorado, on January 10, 2019. The parade marked the start of the premier livestock, rodeo, and horse show in the United States, in its 113th year. #