This was the original alignment of the N&W's single track mainline through the communities of Twin Branch and Marytown in McDowell County, WV. The current double-tracked mainline was constructed around 1907. The old mainline track remained in service for a number of years as the Twin Branch Branch. It tied into the current mainline at milepost N408 between Twin Branch Tunnels #1 and #2, and then again at the east end of the Claren middle track near the N409.3. The Twin Branch Branch served two spurs to the Twin Branch mines and a spur to the Marytown tipple.