The St. Maries River Railroad (reporting mark STMA) is a shortline Class III railroad that operates 71 miles of freight service in northern Idaho.
The St. Maries River Railroad began service on May 23, 1980, over trackage that previously had been owned by the bankrupt (and now-defunct) Chicago, Milwaukee, St. Paul & Pacific Railroad, also known as the Milwaukee Road.
The railroad also operated on the Milwaukee Road's former Elk River branch line between St. Maries and Bovill, Idaho.
[1] For several years from 1980 until the mid-1980s, Potlatch also owned and operated 45 miles of adjoining former Milwaukee Road trackage, between St. Maries and Avery, Idaho, as a private logging railroad that connected with the St. Maries River Railroad.
The federal government condemned the logging line between St. Maries and Avery in the mid-1980s, prompting its shutdown.