The Porcupine River is a 916 km (569 mi) tributary of the Yukon River in Canada and the United States. It rises in the Ogilvie Mountains north of Dawson City, Yukon, Canada. From there it flows north through the community of Old Crow, veers southwest into the U.S. state of Alaska, and enters the larger river at Fort Yukon, Alaska. It derives its name from the Gwich'in word for the river, Ch'oonjik, or "Porcupine Quill River".

The Yukon River is a major watercourse of northwestern North America. From its source in British Columbia, it flows through Canada's territory of Yukon. The lower half of the river continues westward through the U.S. state of Alaska. The river is 3,190 kilometres (1,980 mi) long and empties into the Bering Sea at the Yukon–Kuskokwim Delta. The average flow is 6,400–7,000 m3/s (230,000–250,000 cu ft/s). The total drainage area is 833,000 km2 (321,500 sq mi), of which 323,800 km2 (125,000 sq mi) lies in Canada. The total area is more than 25% larger than Texas or Alberta.