NASA’s image of the day shows paw paw bends of the Potomac River and canal. The stunning image was captured by the Operational Land Imager (OLI) on September 27, 2016. The canal measures 297 kilometers and was constructed in 22 years starting from 1828. While the image shows only a 97 km stretch of the canal.
The canal has a high historical value as it played an important role in transporting goods, primarily coal. The canal, towpath, and surviving system of locks and structures, are now a national historic park.
Original plans called for the canal to wind all the way to Pittsburgh, Pennsylvania, but cost overruns and construction delays prevented that from happening. One of the more infamous delays occurred near Paw Paw, West Virginia. The second image shows a detailed view of the region, where the Potomac takes on a sinuous shape. The meanders in this view are confined between parallel ridges running northeast to southwest.
Meanders along the rivers and streams in this region are not uncommon; they are visible in multiple locations in the top image. But the Paw Paw Bends curve to such a degree that engineers determined they would save 10 kilometers (6 miles) of canal by bypassing four of the bends incised deep in the bedrock. They decided instead to route the canal through the ravine of a tributary, and then excavate through shale rock to construct a 950-meter-long tunnel (3,118 feet), the largest structure along the canal. Work started in 1836 and was completed 14 years later—12 years longer than first planned.