The Tionesta Valley Railway was a North-central Pensylvania logging road(Clarion county,I believe) .It supplied charcoal and chemical processing plants with soft wood,the most prevelant being hemlock. It ran at least into the mid to late 1940's. There's some good pics in Mike Koch's "Steam and Thunder in the Timber" if you can get your hands on a copy. There was at one time a great many narrow gauge common carriers as well as industrial lines in PA. Most were short lived,either disappearing entirely or wound up being standard gauged. One of my personal favorites is the Bradford,Bordell & Kinzua. It's total lifespan was about 25 years,from the 1880's until about 1906 as I recall. One piece of rolling stock from the BB&K survives today. It had been the business car, and after the line folded it became the "ORBISONIA" on the East Broad Top.