The coastal plain of North Carolina was once covered by a near-continuous blanket of longleaf pine, a tree that produces a thick, fragrant resin. British colonial policy turned the colony into a naval stores factory: settlers tapped pines for resin, boiled it down into pine tar, and floated barrels down the rivers to the ports at Washington, Bath, and Edenton. The pine tar caulked the seams of wooden ships. The pitch sealed ropes. The masts came from the tallest trees. The Tar River was the highway for all of it. The names of the towns along its course - Louisburg, Rocky Mount, Tarboro, Greenville - mark stages in the tar-shipping economy. Tarboro, especially, was named for the trade. Before the Civil War the state legislature even funded a plan to lock and dam the river for year-round barge traffic between Tarboro, Greenville, and Washington.

There is a Civil War story that purports to explain the river's name, though it is more likely a folk tale grafted onto an older origin. In March 1862, as Confederate forces prepared to abandon the town of Washington to the Union Navy, they sent squads up and down the river to destroy the stocks of cotton and naval stores at Taft's store - over a thousand barrels of turpentine and tar - that might otherwise fall into Union hands. The barrels were rolled into the river, the hoops cut, and the contents poured in. Three months later, a column of Union prisoners of war passing through Washington stopped to bathe. The river bottom, still slick with months-old tar, smeared their bodies head to toe. A Confederate guard reportedly called out, asking what the matter was. A frustrated Yankee soldier answered: 'We have heard of Tar River all our lives but never believed there really was any such place - but damned if we haven't found it, the whole bed of it is tar.' The story is probably exaggerated. The tar in the river was real.

The lower Tar is among the most flood-prone rivers on the Atlantic coast. In September 1999, Hurricane Floyd dumped twenty inches of rain over its watershed and the lower river suffered what hydrologists called a five-hundred-year flood - the Tar crested twenty-four feet above flood stage, with Greenville hit at 29.74 feet, swallowing entire neighborhoods and turning the town into an archipelago. Seventeen years later Hurricane Matthew did much of it again, with the river cresting up to 24.5 feet above flood stage and staying there for three days. The flooding spilled into floodplain hog farms and waste lagoons, fouling water that was still draining months later. For people living in the river towns, Floyd is the dividing line - everything is described as before or after.

The Tar's biology carries one specific endangered species: the Tar River spinymussel, a small freshwater mussel found in limited stretches of the Tar and Neuse basins and almost nowhere else on Earth. Sound Rivers, an environmental group that protects both watersheds, maintains more than a dozen camping platforms along the Tar-Pamlico Water Trail - a paddler's route that runs from the upper river through the cypress sloughs of the lower river and into the tidal Pamlico. Old Sparta, once an important river port between Tarboro and Greenville, has dwindled into a quiet village; the locks and dams the state once planned were never finished. The river runs free, dark with tannin, threading through farms and through the slow, patient bottomland forest that has reclaimed most of its banks.