Heads SW of Mount Page in Yukon, Canada, flows NW and NE crossing the Alaska-Canada boundary several times to Clarence Lagoon, 11.5 mi SE of Demarcation Point, Arctic Plain. 35 miles long. Note that Orth, 1967, references the source of the river as Mount Paige.
On July 27, 1826, Franklin (1828, p. 139) wrote: "This being the most westerly river in the British dominions on this coast, and near the line of demarcation between Great Britian and Russia, I named it the Clarence, in honor of His Royal Highness, the Lord High Admiral."