The entrance of the Pennsylvania Railroad's extension from Tyrone, northwest to Philipsburg and Clearfield opened much of the field to coal mining.
This line bypassed Clearfield and extended south to Mahaffey and eventually into Indiana County.
Other rail lines included the Buffalo, Rochester and Pittsburgh Railroad's extension down Anderson Creek to Clearfield, NYC's extension to Clearfield and down the Susquehanna River to Keating, and the Bell's Gap Railroad, which ran through the southern part of the county through Mahaffey.
Each railroad opened numerous coal company towns such as Surveyor, Croft, Karthaus and Bald Hill on NYC's Susquehanna River line.
Numerous other towns were built such as Gaazam, Glen Richey, Peale, Winburne (Summerville), Hawk Run, Morrisdale and Irvona.