Pennsylvania is one of the premiere trout fishing destinations in the east. The Allegheny Mountains - the local name for the Appalachians - cut a semi-circular swathe through the center of the state and, along with the Allegheny plateau on the north-central border with New York, provide some of the best trout habitat. The upper Delaware River, which defines the northeast border with New York, is an extraordinary fishery, and is fed by numerous small streams flowing out of the Poconos and Blue Mountains (and New York's Catskills). Even the lowlands of the SE support some superb trout fisheries in limestone streams which have become world famous.
Indeed, the state is so big that no one really knows how much trout habitat there is: e.g. streams classified "Class A" by the state have more than tripled from 400 stream-miles in 1983 (when the current classification system began) to more than 1,400 miles in 2008. Every year, new surveys identify additional waters supporting self-sustaining trout populations. The Pennsylvania Fish and Boating Commission ("PAFBC") publishes comprehensive lists of wild trout streams and a number of useful mapping databases that we've made available on our state-of-the-art web map. The Water Quality process identifies thousands of miles of additional cold water stream habitat that has never been surveyed.
Like all eastern states, the only truly native trout is the Brook Trout. Today, most streams in PA are home to exotics: brown trout and rainbows, migrants from trout stocking, now living in self-sustaining populations. Brookies can still be found, though usually only in the smaller, colder streams found in the most pristine habitat.