Cumberland Valley Subdivision

The Cumberland Valley Subdivision ( CV Subdivision) is a railroad line owned and operated by the CSX Railroad (CSX Transportation) in the U.S. states of Kentucky and Virginia. The line runs from Corbin, Kentucky, east to Big Stone Gap, Virginia, along a former Louisville and Nashville Railroad line.

At its west end, the CC Subdivision heads north to Cincinnati, Ohio, and the KD Subdivision heads south to Etowah, Tennessee. The east end is at an interchange with the Norfolk Southern Railway Appalachia District, where CSX trains can proceed south to the Kingsport Subdivision at Frisco, Tennessee, via trackage rights.

History
In 1886, the Louisville and Nashville Railroad (L&N) began to work toward a route through the Eastern Kentucky Coalfield and Southwest Virginia in an effort to connect to the Norfolk and Western Railway (N&W) somewhere near Norton, Virginia. Surveyors identified a route via Middlesboro, Kentucky, a tunnel under Cumberland Gap, and up the Poor Valley. The line was completed to Middlesboro in 1889, and then on to a place called Intermont, Virginia (now Appalachia) where it connected with the Atlantic and Ohio (later Southern Railway). The route was completed to Norton, Virginia (then Prince's Flat) in April 1891.

The L&N began to make way into Harlan County, Kentucky by taking over the under-construction Wasioto and Black Mountain Railroad, completing that line to Harlan, Kentucky in 1911. Further progress was made in 1930, when L&N completed what was then the Martin's Fork Branch and constructed a 6,244-foot tunnel under the Cumberland Mountain at Hagan, Virginia. Original plans called for an extension to connect with the Carolina, Clinchfield, and Ohio Railway (better known as the Clinchfield Railroad). However, plans were scrapped due to financial uncertainty, and the L&N decided instead to connect the new tunnel to the existing Middlesboro–Norton mainline via a switchback.