Leadore is an incorporated small town in Lemhi County, Idaho, United States. The population was 105 at the 2010 census. The town of Lea…Leadore is an incorporated small town in Lemhi County, Idaho, United States. The population was 105 at the 2010 census. The town of Leadore dates from 1910, when the Gilmore and Pittsburgh Railroad was constructed from Armstead, Montana, over Bannock Pass and into the Lemhi Valley. This occurred because the original location for the train station in the town of Junction had to be altered when the owner of the land refused to sell. The town was home to the railroad's repair shops, and was the point where the railroad's branch line to Gilmore connected with the main line. Though the railroad ceased operating in 1939, Leadore has remained the largest town in the immediate area.