DCHP-1 Online
jumping-off point 
1 a place, usually a town, where one leaves the railway or other link with civilization to proceed into the wilderness.
See also: jumping-off place (def. 2a)
- 1953 This egregious place, not far from the wilderness of the Canadian Shield, grew up as a "jumping off point" for the bush. . . .
- 1966 The city [Edmonton] was one of the main jumping-off points . . . for the long trek to the gold country.
2 any starting place.
See also: jumping-off place (def. 2b)
- 1958 Prince George is your jumping-off point for another great excursion. . . .
- 1953 This egregious place, not far from the wilderness of the Canadian Shield, grew up as a "jumping off point" for the bush. . . .