To keep the record straight it is generally considered that Oregon American of Vernonia operated the last real logging railroad in the USA which closed in 1957.
After that there were numerous log hauling lines - many of which had originally been logging railroads as well. The last regular service shay was at Klickitat, the last use of a steam engine is a little murkier - Rayoneer had the 110 (I think) articulated that operated until 1967 but the Willamina and Grande Rhonde (LP&N) has a "standby" Mikado that had been there for years and was never actually taken out of service that was not sold until 1980 (!) to the Virginia and Truckee at Virginia City.
Medco ran the last Willamtte in 1961. Georgia Pacific ran thier tank engines and disconnects out of Toledo until Dec 31 1959. etc etc
The last old-time log hauler in Oregon was the Weyerhauser woods railroad at Sycan for the K Falls operation. It closed in 1990.
The last in Washington is the Weyerhauser at Longview, but it mostly hauls mill waste - though still in operation. Simpson of Shelton has only recently shut down what little was left of thier expansive looging railroad network.
Idaho still has the St Maries Railroad hauling logs. Last I heard the logging branch out of Orofino (Camas Prarie) had been pulled up, but them someone else told me it was still available to haul logs?
Nope, none were narrow guage.
Last narrow guage log hauler in Oregon was Sumpter Valley/Oregon lumber Co. and in Washington Biles-Coleman. Lon Wall
www.pacificmodelloggerscongress.com