The Norfolk & Western Railway built its first eight "Mountains" in its shops in Roanoke, VA during 1916. These locomotives (Class K-1, road numbers 100 through 107) had 29 x 28 cylinders, 70" drivers, a boiler pressure of 220 psi, exerted 69,920 lbs of traction effort and weighed 347,000 pounds. The following year another eight (road numbers 108 through 115) duplicates of the first Class K-1s, were built. All of these 4-8-2s entered passenger service.

During World War I, the USRA took over the railroads and it supplied the N&W with ten "Heavy Mountains" (road numbers 116 through 125). They were built by the American Locomotive Company and were designated as Class K-2 . These locomotives had 28 x 30 cylinders, 69" drivers, a 200 psi boiler pressure, exerted 57,950 lbs of tractive effort and weighed 359,460 pounds. Another twelve (road numbers 126 through 137) were bought from the Baldwin Locomotive Works in 1923. This group of twelve, designated Class K-2a, were identical to the ten built by ALCO in 1919. Later, road numbers 116 through 137 were up-dated and received semi-streamlining, 70" drivers, an increased boiler pressure of 220 psi resulting in 62,832 lbs of tractive effort.

In 1926, the Roanoke Shops built ten "Mountains" (road numbers 200 through 209). These locomotives, designated Class K-3, had 28 x 30 cylinders, 63" drivers, a boiler pressure of 225 psi and exerted 68,880 lbs of tractive effort. They were built for through freight service, but because they could not provide the speed needed they were assigned to coal freight. This group was later sold to the D&RGW and the RF&P, during World War II, only to come back as W&LE numbers 6801 through 6810.

There are no surviving N&W "Mountains".