(Source: Storm King’s Thunder, page 111)

The Triboar Trail starts at Triboar, heads west, goes around the north of the Sword Mountains, cuts past Phandalin, and ends in the High Road.

Micro-Worldbuilding Opportunity: There has got to be more than just a Mission House where the Triboar Road meets the High Road, wouldn’t you say? I'm thinking that there would be a village there that will deal with the intersection.