This route through the front ranges of the Canadian Rockies and now occupied by Lake Minnewanka, was established by the ancestral Bow River. It is thought that the huge volumes of glacial till blocked the valley as the last iceage ended some ten thousand years ago, forcing the river to follow and deepen a new channel from the area of Banff Townsite.
Devil's Gap was regularly used as a path into the mountains by the natives, in fact one of the oldest archeological sites in the area is near the western end of Lake Minnewanka. According to Gillean Daffern, fierce skirmishes between the Blackfoot and Kootenai Indians were fought in the area and are the source of a legend telling of a ghost seen going up and down the Ghost River, picking up the skulls of the dead. This appears to be the source of the names related to ghosts and phantoms.
Phantom Crag is a low but impressive peak that stands to the north of Devil's Gap.
Although originally a pass separating waters that eventually flowed through the Ghost Lakes that occupied the valley now containing the Lake Minnewanka Reservoir into the Cascade River from the Ghost River Valley, Devil's Gap in no longer "technically" a pass as the Ghost River is diverted through the gap and into the reservoir.
The route was followed by George Simpson in 1841. He described it in his journal as follows, "In the morning we entered a defile between mountain ridges, marching for nine hours through dense woods. This valley, which was from two to three miles in width, contained four beautiful lakes, communicating with each other by small streams; and the fourth of the series, which was about fifteen miles by three, we name after Peechee as being our guide's usual home." [see Mount Peechee]
A Stoney Indian described it to James Hector while Dr. Hector was camped below Cascade Mountain. The Stoney told Hector that he had, "come though the first range by a pass to the south of Devil's Head in which he says there is a lake the length of a half days march, where they catch the finest trout and white fish in the country. At the upper end of the lake, which sends a stream into Bow river just below where we camped (Cascade River), he says there is a "height of land" to be crossed, and from the other side of which rises Deadman's River."
James Hector referred to the pass as "Cascade Mountain Pass." [McCart]
The series of lakes in the gap became Lake Minnewanka when a dam was built across the western end of the valley in 1912 and then a higher one in 1941.