The parent was asking about getting down to the SF Bay from somewhere in Sierras. I'd have to study a map in detail but I doubt there are much in the way of east/west routes in that area. Also, while there are navigable waterways in cities they tend to be very limited. There's often one river in older cities that flows through the center somewhere.
It really depends on the watersheds. You can get to Boston from pretty far north but you would have to cheat by going down the coast from the mouth of the Merrimack River which I think captures all the rivers in southern NH/northern MA.
It really depends on the watersheds. You can get to Boston from pretty far north but you would have to cheat by going down the coast from the mouth of the Merrimack River which I think captures all the rivers in southern NH/northern MA.