The CSX Kingwood Subdivision or the M & K branch is the only remaining section of the former Morgantown and Kingwood Railroad. The M&K RR was constructed in the early years of the 20th century to haul the enormous coal resources found between Rowlesburg and Morgantown, WV. Completed in 1907, this line was absorbed by the B&O in 1920.
From Rowlesburg (MP 254.4), where the Rowlesburg Southern once headed away to the south, and bridging over the Youghioghany River to the 15 mph crossovers at MK Tower (MP 253.9), which closed on December 8, 2010, where there is a junction with the M&K branch off to the north, the double track line, current-of-traffic (Rule D-251) on Track 2 and CTC on Track 1, with speed limit 45 mph for fast freights and 40 mph for slow freights, heads curvily northeast, ascending the Cranberry Grade, past the crossover at McMillan (MP 252.5), where the speed limit drops to 30/15, Amblersburg, the end of the siding on the north side at Rodmer (MP 247.0), and a detector at MP 243.9 on Track 2, turning curvily east-southeast to the top of the Cranberry Grade at Terra Alta (MP 242.0), reached by a very evident vertical curve at the top of the grade, where Rule D-251 takes over on Track 1 as well as Track 2.
The line now remains at this relatively high altitude for some distance, turning south and then east past crossovers at Rinard (MP 241.0), CA Tower a detector at MP 238.1 on Track 1, 35 mph on Snowy Creek curves as the line turns south and then southeast, a 101 car siding on the south side at Cornith (MP 238.2), and Hutton (MP 237.6), 35 mph on curves near MP 235 as the line turns northeast and then curvily south-southeast, Oakland (MP 232.2), where the beautiful stone depot is on the north side of the line, with a 30 mph speed restriction on the curve, with a road crossing just to its east, and east-northeast, past Mountain Lake Park (MP 229.6), crossovers at Deer Park (MP 226.2), a detector at MP 225.9 on Track 2, east-southeast and then northeast, with a 40 mph speed restriction from MP 224.4 to the 1st curve west of Swanton, and the 2628 ft. Summit of the Alleghenies at Altamont (MP 223.4), where there are crossovers, AM Tower, and a 100 car siding on the south side.
The descent of the Seventeen Mile Grade now begins, past Wilson (MP 222.5), a detector at MP 221.9 on Track 1, a 30 mph speed restriction on the 1st curve west of Swanton, Swanton (MP 220.1), crossovers at Strecker (MP 217.3), and Frankville, turning curvily east-southeast past the center third track from BD Tower at Bond (MP 212.6), where the speed limit drops to 25 mph on the south track (Track 2), CTC-operated on Track 2, to Big Curve (MP 211.1), where the speed limit on Track 2 reverts to 45/40 and Rule D-251 resumes on that Track, the end of the center track at Bloomington (MP 208.6), the bridge over the Potomac River and the former West Virginia Central line from Elkins, both of which then turn southeast, West Virginia Central Junction (MP 207.8), where the eponymous line connects in on the north side before turning away and crossing the river to Westernport.
The line turns east and then north-northeast, following the south bank of the Potomac, turning east-southeast past the crossover at Piedmont (MP 206.6), foot of the grade, where a connector from Westernport, across the river, once trailed in from the north, 40 mph on curves at MP 205 as the line and river turn southeast, east, and east-southeast, West Keyser (MP 203.1), where an extra track starts on the south side, the yard on the south side, and the crossovers at Keyser (MP 201.6), location of Z Tower, where a narrow-gauge line once headed away on the south side.
East of Keyser, the line turns east and then north and runs across the Potomac River valley to Cumberland, MD, with 40 mph on Bull Neck Curves, a turn northwest across the river, north at Twenty-First, where the former Western Maryland line which once ran independently on the east side of the line later joined the line at this point, northeast, north past Dawson, northeast, east, north-northeast past Black Oak, east, northeast, north, northeast past crossovers at Rawlings (MP 191.5), where the extra track on the south side ends, Bier and Lowndes, east past Potomac and crossovers at McKenzie (MP 187.5), where there is a 25 mph speed restriction, with 15 mph for diverging movements, where a cutoff line once headed directly east to Patterson Creek, north, north-northeast past Brady, east past Amcelle, north to Roberts, north-northeast and east, with 30 mph speed restriction on curves, past Kelly-Springfield, and curvily north-northeast, with 30/25 on the curves north of the Kelly-Springfield Tire Plant, onto the concrete viaduct over the Western Maryland main line and Georges Creek, and east-southeast at the crossovers at Viaduct Junction (MP 178.9), with ND Tower on the north side (in the vee), just west of the Sand Patch line trailing in on that side at a double junction (15 mph on the junction), and then south, past crossovers at Baltimore Street (MP 178.4), location of BS Tower, where there is a 25 mph speed restriction on the road crossings, and crossovers at Cumberland (MP 178.3).