Action may be required on your Trains.com account in order to continue accessing content. Click here to learn more.

Photos & Videos Videos Union Pacific Challengers as they appeared in service

Union Pacific Challengers as they appeared in service

By | August 3, 2021

Watch this video featuring Union Pacific 4-6-6-4 Challenger locomotives

This content is available to Trains.com Unlimited Members only.

Want unlimited access to Trains.com?

Learn More Start Your Free Trial

You’ll get complete access to all content on Trains.com from our family of brands, PLUS thousands of issues in the archives, video series and workshops, live webcams and more!

Magazine subscribers enjoy access to online subscriber benefits.

Learn more about magazine subscriber access

Already a magazine subscriber? Sign In

Card image cap

Classic Trains

Trains Go To War: Railfans in Vietnam

Card image cap

Classic Trains

Trains Go To War: An overview

Card image cap

Classic Trains

Horseshoe Curve in 1969

Card image cap

History According To Hediger

Classic Trains

History According to Hediger: Anchors not aweigh!

Shop our Trains.com Store

Members enjoy 15% off any purchase in our store. Join Today!

Amtrak’s History Through Its Equipment

This book brings to life the evolution of the U.S. national passenger rail system, from its patchwork beginnings to today’s high-speed locomotives and cars.

Classic Trains Hat

Celebrate your favorite historical railroading magazine with this exclusive Classic Trains hat.

Classic Trains 2026 Calendar

The Classic Trains calendar is back for 2026 featuring 12 historic railroad photos.

Fallen Flags: Southern Pacific Remembered

This tribute to one of the most iconic railroads in history features in-depth stories, captivating photography, and rare insights into the Southern Pacific system.