The Fall line, or fall zone, in North Carolina is defined in geological terms as the line of erosion between the piedmont and the coastal plain regions at which hard, erosion-resistant rocks descend into softer, eastern rocks. Running through Richmond, Montgomery, Moore, Lee, and other counties, the fall line is particularly apparent in rivers as the place past which boats can no longer navigate because of the occurrence of natural falls or rapids. The fall line has thus greatly influenced transportation, settlement location, population distribution, and industrial development in North Carolina.
Water transportation was the cheapest and most reliable method of moving goods and persons in the early years of the state's development, so it was natural that areas near fall lines in rivers often became population centers. These fall lines also became known as "break-in-bulk points" because at them large shipments coming in on water vessels would be rearranged into smaller lots for further land transportation. Points on rivers adjacent to the fall line also provided a source of energy to run water mills and other important commercial ventures; consequently, the state's early development was concentrated at the fall line along its major eastern rivers. The towns on the fall line of the Tar River were Tarboro, Greenville, and Rocky Mount. On the Neuse River, Kinston, Smithfield, and Goldsboro were developed on the fall line. Weldon was formed on the Roanoke River fall line, Hillsborough on the Eno River fall line, and Alamance on the Alamance Creek fall line.
The fall line remains important in the modern day for the measurement and management of pollution in North Carolina's rivers. The difference in soil types and water flow on either side of the fall line allows scientists to study the effects of pollutants introduced into the rivers, serving, in part, as the basis for various pollution-related regulations.