They could only pass through selected places called drinking water gaps. On the other hand, the valleys in central Pennsylvania are linked by the Susquehanna River and its smaller rivers. This allowed for canals being in-built the 1830s. By clicking “Accept All Cookies�? you conform to the storing of cookies https://www.tjcyindustrialchem.com/news/what-is-sodium-tripolyphosphate-stpp-used-for.html