Saluda Grade is the steepest standard-gauge mainline railway grade in the United States. Owned by the Norfolk Southern Railway as part of its W Line, Saluda Grade in Polk County, North Carolina gains 606 feet (185 m) in elevation in less than three miles between Melrose and Saluda. Average grade is 4.24 percent for 2.6 miles and maximum is 4.9% for about 300 feet.
Captain Charles W. Pearson was assigned to select a route for the Spartanburg and Asheville Railroad to ascend the Blue Ridge front; the area where the rolling hills of the Piedmont end at the foot of the Blue Ridge Mountains. Despite numerous surveys, no route was available for a railroad to ascend the mountains at a tolerable grade, and the best route followed the Pacolet River valley and gorge. The line begins its climb at the bottom of Melrose Mountain, where Tryon is today, at 1,081 feet (329 m), and continues on the south side of the Pacolet valley. At Melrose the Saluda Grade begins and climbs to the town of Saluda, cresting in the center of town at an elevation of 2,097 feet (639 m).
Because of accidents involving downgrade runaway trains in the late 1880s, the then Southern Railway built two runaway safety spur tracks. These were originally manned junctions, which were always switched to a 60-foot (18 m) pile of earth, which could stop downgrade runaway trains. Only upon hearing a whistle signal from the downgrade train would the signalman manning the spur junction throw the switch to keep the train on the main line. In later years, CTC signaling was installed along with automated switches and timer circuits for the one surviving runaway safety track at the bottom of the grade at Melrose. Trains running downgrade were required to maintain 8 mph until reaching the runaway track switch. This would allow a timer circuit to determine if a train was under control, which would align the switch for the runaway track at Melrose to the mainline. Any speed greater than 8 mph, and the switch would remain aligned for the runaway track. Saluda Grade was one of the few grades in the country where uphill trains could travel faster than their downhill counterparts. Most uphill trains had to double or triple the grade, splitting the train into sections to be taken up the grade to Saluda one at a time and reassembled there for the rest of the trip to Asheville.
Norfolk Southern suspended freight traffic between Landrum, South Carolina and Flat Rock, North Carolina in December 2001, thus ceasing operations on the Saluda Grade. Norfolk Southern has not abandoned the line and the rails remain in place, but they are cut and out of service. Norfolk Southern inspects and maintains the right-of-way, removing fallen trees and spraying herbicide on encroaching vegetation, but at least three washouts of the roadbed have occurred between Saluda and Tryon. Talks of a passenger train excursion and a Rails-to-trails conversion have made no headway in recent years, and Norfolk Southern states it does not intend to abandon the line.
- "Steepest main line U.S. railroad grade falls silent". Trains: p. 12. March 2002.
- Don Ball, Jr. (1978). America's Colorful Railroads. New York: Bonanza Books. p. 91. ISBN 0-89169-517-6.
- Lori Sondov (January 8, 2003). "Activists launch effort to rescue piece of history in hopes of restoring railroad service thru the Tryon - Saluda area". Greer Citizen.
- "Norfolk Southern denies Tryon Streetscape railroad encroachment". Tryon Daily Bulletin. December 28, 2011.