The One Minute Geographer: The Portage Site Line

Base map showing cities as clusters of dense population from http://www.nber.org/papers/w16314 Red numbers added by the author. See text below for the list of numbered cities and rivers.

This post about portage sites and cities that grew up at or near them is really a continuation of my previous post about the east coast’s Fall Line. The Fall Line (capitalized) has come to have a geological meaning as the zone where falls and rapids form where the Appalachian Piedmont meets the Coastal Plain. These features present a barrier to navigation up and down rivers. As we saw in the earlier post, most of these rivers flow into the Atlantic but in a few cases such as at Columbus GA, and at Montgomery and Tuscaloosa AL, the rivers flow into the Gulf of Mexico.

For the same reasons — geological barriers to navigation of the rivers (falls, rapids, narrowings at gorges) — we can define a continuation of a fall line called the portage line through the southern United States along other rivers flowing into the Gulf Coast all the way through Texas. This is shown on the map at the top of this post. And we’ll see in a future post that we can make a similar definition for falls along rivers in New England.

The importance of portage sites pre-dates European settlement. Native Americans/American Indians had to drag their canoes and their goods around these barriers. Later French and other European fur trappers did the same. The word portage comes to us from the French, derived earlier from Latin portare — to carry.