It's the birthplace of dry fly fishing in the US. Fly fishing has been practiced in this country since colonial days, for bass as well as trout. (Probably even earlier, as several native American tribes apparently used the feathered hook as well.)
The early dry flies from the Catskills looked pretty much like they do today, except for slight differences in proportions - we're talking about flies with names like Cahill, Hendrickson, and Quill Gordon.