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]

The website of Rocky Mountain House National Historic Site notes that four fur trade post have been discovered there:

1958 – Acton House of the Hudson’s Bay Company built in 1799 was found.
1966 – Excavations took place at Rocky Mountain House, the Hudson’s Bay Company Post of 1868-1875.
1975 – Rocky Mountain House of the North West Company built in 1799 was found.
1975 – Rocky Mountain House, the Hudson’s Bay Company post of 1835-1861 was found.

Archaeologists also searched for a fifth post. It once stood where the river runs now. The Hudson’s Bay Company built this temporary post (1865-1868). It housed fur traders and their families until the last post was finished.