1950 Map of Harrisburg

Settlement patterns follow the fertile limestone valleys, from the Lebanon Valley to the Cumberland Valley. Urban centers like Harrisburg, Lancaster, and Pottsville appear at the peak of their mid-century development, connected by emerging modern infrastructure like the Pennsylvania Turnpike. The geography is defined by parallel ridges such as Blue Mountain and Jacks Mountain, which shaped the expansion of historic boroughs like Lewistown and Sunbury along the Juniata River and the river's West and North branches.