 The Central State Normal School , established to train teachers for central Pennsylvania , held its first classes in 1877 at a site overlooking the West Branch Susquehanna River . The small school , with <unk> below 150 until the 1940s , eventually became Lock Haven University of Pennsylvania . In the early 1880s , the New York and Pennsylvania Paper Mill in Castanea Township near Flemington began paper production on the site of a former sawmill ; the paper mill remained a large employer until the end of the 20th century . 
