The Baltimore & Ohio Railroad reached Cumberland, MD in November 1842 after construction of the East End, today's Cumberland Subdivision. For the next seven years, the B&O contemplated routes to the west, to fulfill the promise in it's name: "& Ohio". The preferred route would have crossed southwestern Pennsylvania, reentered Virginia (there was no West Virginia yet), and run due west to Wheeling, following the old National Road fairly closely. Political pressure by both the state of Virginia and the Pennsylvania Railroad precluded this solution, however.
Many people lost their lives in the construction of this rugged piece of railroad, and many more lost life and limb operating it in the following years. B&O had to invent a lot of the technology
Traffic levels soon climbed to a point that double tracking large parts of the railroad was required, a task completed in the 1870s. In line with constant improvements on the eastern half of the mainline, the Cumberland Sub (East End), also the West End underwent changes with the aims of increasing capacity and train speeds, and lowering costs. Starting around 1910, the new Kingwood Tunnel between Tunnelton and West End was bored and the mainline relocated east from there to Blaser. The advent of the Mallet locomotive brought about the construction of M&K Junction near Rowlesburg as a helper base, the relocation of helper facilities from Newburgh to Hardman, and a massive increase of train tonnage due to the new engines' superior pulling power.
As was the case on every railroad in the country, dieselization changed everything. Many of the important assets of the 30s are gone or stand unused, like for instance M&K Jct.
The moniker "West End" harks back to this line being the western part of B&O's "Main Stem". More officially, it was the West End Subdivision of the Cumberland Division up to the Chessie merger. Chessie called it the Mountain Subdivision of the Maryland Division. For CSX it's the Mountain Subdivision of the Allegheny Division.
The West End was closed as a through route in August 1985 when Chicago traffic was diverted onto the Keystone Sub over Sand Patch. Apart from daily Huntington-Cumberland manifests Q316 and Q317, the predominant commodity carried on West End rails today is coal. Coal had always been important, as the railroad slices through large coal reserves over most of it's mainline run. Trainload after trainload of the black diamonds also originated (and continue to do so) from the coal fields south and northwest of Grafton, predominantly eastbound over the Mountain Sub. The average day will see around three eastbound loaded drags and an equal number of returning empties westbound; though heavily depending on the season and the boom-bust cycles of the coal economy.
At Tunnelton, the interchange with the dormant West Virginia Northern shortline stills exists. The old Morganton & Kingwood, today's Kingwood Subdivision, connected to the Mountain Sub at M&K Junction across the river from Rowlesburg. The connection was severed after the single remaining shipper quit, a sawmill at Caddell, the end of the track. The last two remaining coal loaders, one also at Caddell and the other Patriot Coal's facility across the river from Manheim, closed in 2001. The last remaining coal loader on the West End is now the Whitetail Mine near West End, reached via the Whitetail Industrial Track.
Even today, the West End has lost nothing of it's rugged beauty, and solitary remoteness. It also continues to be CSX's proving ground for new technology, as evidenced by the first SD35s, Super-Series wheel-slip control system in the SD50s, AC propulsion, and radial truck technology. As CSX's latest improvement, the new, heavy 500-series "Magnum" GE AC4400CWs debuted on coal drags in 2001. Most trains operate with helpers, either on the head end, midtrain, or shoving on the rear.
The 2000s saw the closing of the remaining active towers on the West End, Z Tower at West Keyser in 2009 and MK Tower at Rowlesburg in 2011. The resignaling that came with it has drastically reduced the number of active B&O color position light signals. As of 2011, the only remaining stretches are Fairgo to High Rock and Piedmont to Corinth with the exception of 37 Water Station, a total of roughly 47 miles.
This page provides a list of Signals & Stations along with a track schematic.
You can access a number of images taken along the subdivision here. The volumes are arranged chronologically.