The North River begins on the forested slopes of South Branch Mountain in Hardy County. From there, it flows northeast for 47 miles through a sparsely settled countryside of forested hills and mostly agricultural bottomlands to its confluence with the Cacapon River at Forks of Cacapon. The North River is the Cacapon's largest tributary, with a drainage area of 204.71 square miles and 16 named tributaries of its own.

The North River flows past an old tannery in Rock Oak, then through a gap in Short Mountain into Hampshire County and the small town of Rio. The North then runs through a broad agricultural valley past the small communities of Delray and Hanging Rock, past historic North River Mills and Ice Mountain before entering the Cacapon River.

In colonial times, the Great Wagon Road crossed the North River at North River Mills, located between Sandy Ridge and Grape Ridge, on its way west from Winchester, Virginia. The area's fertile bottomlands, in addition to the system of land grants by Lord Fairfax, encouraged settlement, and place names remind us today of this region's colonial history. For example, George Washington's personal physician, Dr. James Craik, took advantage of the Lord Fairfax land grants and speculated on land in the North River Mills area; local residents use water from Craik's Spring to this day.

Like others in West Virginia, the people who settled the North River watershed made use of the natural resources they found. Tanneries in the headwaters community of Rock Oak prepared hides using tannins extracted from oaks and other local vegetation. Lime kilns, such as the one on Hiett's Run once operated by Perry Gess, converted the limestone found in parts of this watershed to lime for use in agriculture and construction. And the water itself drove mills, like two of the three mills that gave the once bustling community of North River Mills its name.