North West Co. post at junction of Mattawa and Ottawa rivers. It was first built by the North West Co. about 1784, probably on the site of an old French fort. It was an important station on the canoe route from Montreal to Fort William, the route here leaving the Ottawa river. Another route proceeded north by lake Timiscamingue to Fort Abitibi and James Bay. The North West Co. followed the Mattawa route to the west (the old French route) until about 1800 when the lake route via Yonge Street was adopted, although the Mattawa route was in constant use for a century. Mattawa House was maintained by the North West Co. as an outpost of Fort Timiscamingue and after the union of 1821 the Hudson's Bay Co. continued to operate the post. After the opening of the Canadian Pacific Railway, Mattawa became the headquarters of posts in that region for a decade. Gradually declining in importance it was finally closed about 1915.