The Baltimore & Ohio reached what today is West Virginia when it bridged the Potomac River at Harpers Ferry in 1837. It reached the far (Maryland) side in 1834, then paused for two years pondering routes to take in Virginia before constructing its first river crossing. Cutting corners wherever possible, the contractors continued construction at breakneck speed and reached Cumberland, MD, 97 miles to the west, in 1842.
Early on, Martinsburg became an important maintenance base, still very much in evidence today courtesy of its twin roundhouses and associated shop buildings. B&O's traffic levels began to soar when "soft" (bituminous) coal came into demand during the 1850s. The competing C&O canal wasn't finished to Cumberland yet, and the railroad was half-forced into carrying it's first volume shipments of coal - a commodity it would come to rely on in the years ahead.
Interrupted only by the War between the States, the railroad continuously rebuilt, expanded and improved its physical plant until the 1940s. Important milestones where the introduction of a block system (1892), the second (1894) and third (1931) crossings at Harpers Ferry, the CR&PV low-grade line between Cumbo and Cherry Run, and the Patterson Creek Cutoff (1904).
Reference to this line as the "East End" stems from B&O calling it the East End Subdivision of the Cumberland Division until the Chessie era. B&O's main line, or "Main Stem" as it was initially called, consisted of the East End, and the West End, Cumberland to Grafton, today's Mountain Sub. The East End then became the Cumberland Subdivision of the Maryland Division in Chessie days, and finally today is CSX's Cumberland Subdivision of the Baltimore Division.
Without doubt the most impressive, thorough, and expensive improvement, however, was the construction of the Magnolia Cutoff between 1913 and 1915. This project is fabulous even by today's standards, both in terms of achievement and construction time. Today's CSX mainline still follows the cutoff route between Orleans Road and Okonoko, while the old mainline is a handy railfan access road.
Currently, CSX is closing the last towers along the line. R Tower, pictured on the right, was removed from Miller and transported to nearby Martinsburg in February, 2001.
In terms of traffic levels, the East End is as big as ever. This is still very much the main east-west artery of the combined CSX system, carrying around 25 freights each way daily, in addition to Amtrak's Capitol Limited, and Marc commuter trains east of Martinsburg. The overwhelming majority of movements is overhead manifest, intermodal, and coal traffic moving between the Mountain and Keystone subdivisions to the west and the Metropolitan and Capitol subs to the east.
Historically, the East End, or Cumberland Subdivision as it is called today, has had few online shippers, but those few created significant amounts of traffic. The Frog Hollow and Kelly Island Industrial Tracks, connecting to the mainline at NA Tower, originate the "Stone Trains", solid blocks of limestone destined for steel mills in Pittsburgh. In addition, the tie treatment plant at Green Spring and the US Silica complex at Berkeley Springs still exist. The latter is located on the Berkeley Springs branch joining the main line at Hancock and is the raison d'etre for the branch, the small yard at Hancock, and the local serving it.
In addition to the South Branch Valley (SBVR) short line interchange, Green Spring is notable in that it is the location of a weigh-in-motion scale used to weigh eastbound coal trains.
The Lurgan Subdivision, in former times the Western Maryland connection, still diverges at Cherry Run, leading to Hagerstown, MD. Apart from the SBVR, the only "foreign road" connections exist at Shenandoah Junction, with Norfolk Southern, and near Martinsburg with the Winchester & Western.
This page provides a list of Signals & Stations along with a track schematic.
A Railfan Guide is available to guide you along the Cumberland Sub from Point of Rocks to Cumberland. It is about 80 KB of text divided into four chapters. Print it out along with the Station List, and take it with you the next time you're "down on the river".
You can access a number of images taken along the subdivision here. The volumes are arranged chronologically.