Prince Edward Island sits in the Gulf Of St Lawrence and to somebody "from away" like me, it seems to be divided into three distinct sections. The north-west of the Island is a medley of Irish and Acadian settlers; the eastern end seems to be more Scottish and the centre, which includes Summerside and Charlottetown, had a more sophisticated nucleus of old merchant, shipbuilding and fox breeding families. Like any urban area, families from east and west, and like me, from away, have gravitated to commuting distance from employment.
If you live "across" (on the mainland of Canada) and go to western Canada, you go out west. If you live on Prince Edward Island and go to the western end of the Island, you go "up" west. Being directionally challenged and someone who can get lost in a small mall, I assume the "up west" is because you're also going north, but I wouldn't want to be quoted on that.