Mount Washington Cog Railway

The Mount Washington Cog Railway, also known as the Cog, is the world's first mountain-climbing cog railway. The railway climbs Mount Washington in New Hampshire, United States. It uses a Marsh rack system and both steam and biodiesel-powered locomotives to carry tourists to the top of the mountain. Its track is built to a 4 ft 8 in gauge, which is technically a narrow gauge, as it is 1⁄2 inch less than a 4 ft 8+1⁄2 in standard gauge.

It is the second steepest rack railway in the world after the Pilatus Railway in Switzerland, with an average grade of over 25% and a maximum grade of 37%. The railway is approximately 3 miles long and ascends Mount Washington's western slope, beginning at an elevation of approximately 2,700 feet above sea level and ending just short of the mountain's summit peak of 6,288 feet.