Although its primary purpose today is as a rail route for coal and freight and as a water tunnel from the Pacific watershed to the Denver area, it also sees use by the California Zephyr (the tunnel's apex elevation of 9,239 feet (2,816 m) is the highest point on the Amtrak network) and the Winter Park Express.

The Moffat Tunnel, a 6.2-mile engineering marvel located under the Continental Divide in Colorado, is a critical link for both passenger and freight rail in 2026. The primary passenger service is the Amtrak California Zephyr, which runs daily between Chicago and Emeryville (San Francisco Bay Area). This route is famous for its stunning views as it climbs the Front Range of the Rockies. Additionally, during the winter months, the Winter Park Express (the "Ski Train") carries passengers directly from Denver Union Station to the base of Winter Park Resort, passing through the tunnel to reach the Western Slope. On the industrial side, the tunnel is a major artery for Union Pacific (UP) and BNSF Railway freight trains, transporting coal, grain, and intermodal containers across the mountains. Completed in 1928, the tunnel eliminated the need for the treacherous "Rollins Pass" route, and it remains one of the highest and most important rail tunnels in the United States, sitting at an elevation of approximately 9,239 feet.