The Clinchfield Railroad is unique in that it's the only American route in Train Sim World to be set in the 20th century. It focuses on 1970s-era freight trains in the hills of Virginia (plus a tiny bit in Kentucky too), complete with the EMD F7A, F7B and SD40 diesel locomotives.
This is probably the only time I'll ever review a US freight route, as they don't interest me in general, but I do like the F7A and other vintage diesels.