Post no. 467 in “Historic forts and trading posts” by Ernest Voorhis [1859–1933]:

Five trading posts were known as Rocky Mountain House North West Co. post on North Saskatchewan river, 1-1/4 miles above mouth of Clearwater river, 3 miles below Hangman’s tree (1790) on north bank of river, 70 yards from river’s edge. It stood on high bank, well adapted for defense as block-houses commanded the fort. Of exceptional strength being in territory of Blackfeet Indians. Hence it was sometimes called “Blackfeet post.”

Built by John McDonald of Garth in 1802, although the first structure was erected in 1799. It was visited by David Thompson in 1800 and 1806 and by Alexander Henry Jr. in 1811. It was the uppermost permanent post of the North West Co. on the Saskatchewan river. Ruins were still visible in 1886. After union of the two companies it was occupied by the Hudson’s Bay Co. for many years and finally discontinued in 1875. The Hudson’s Bay Co. constructed a fort nearby (about 114°59′ w. & 52°22’ N.) called Acton House or Rocky Mt. House, both names being given on some maps. [1]