Question: What is another name for  a defunct standard gauge freight railroad line that operated in the Black Hills that ran from the second-largest city in South Dakotafor a distance of 36.043 miles? 
Sentence (from "Rapid City, South Dakota"): Rapid City (Lakota: "Mni Lúzahaŋ Otȟúŋwahe" ; "Swift Water City") is the second-largest city in South Dakota (after Sioux Falls) and the county seat of Pennington County.
Relevant evidence: Yes