The Empire Builder
Amtrak's Empire Builder is a 2,205-mile route from Chicago, IL to Seattle, WA. In 1981, Amtrak added a section that split at Spokane and followed the former Spokane, Portland, and Seattle Railroad route to Portland, OR. The route and name were a continuation of the Great Northern Railway's flagship passenger service that began in 1929. The name was the nickname of Great Northern founder James J. Hill who in the late 19th century had consolidated a number of subsidiary lines into the nation's only successful privately-funded transcontinental railroad.
Although much of the route passes across the Great Plains and is not particularly dramatic, the passage through the Cascade Mountains in Washington State is quite attractive, and the post-industrial Midwest is interesting if you're into such things.
These photos cover a trip from Seattle to Chicago when I was returning from the 2011 Association of American Geographers annual meeting. My westbound train had been cancelled a few days earlier due to Spring flooding, and flooding was still visible around the Milk River in Montana.