Which region does the Porcupine River drain before joining the Yukon River?

The Porcupine River drains the northern region of the Yukon territory in Canada and the northeastern portion of Alaska in the United States before joining the Yukon River near Fort Yukon, Alaska.1

Rising in the Mackenzie Mountains, the river flows in a great arc, moving first north and then west across the international boundary. It serves as a significant drainage system for the northern part of the Yukon territory, which is characterized by large stretches of flat, poorly drained tundra and widespread permafrost.12