New Brunswick Route 172

The route's northern terminus is at the intersection of Route 780 and Route 1 (exit 56) in Upper Letang, New Brunswick. The road is a continuation of Poor House Hill Road and it also known as Mt. Pleasant Road. From there, it runs west to the community of St. George and passes the Magaguadavic Basin. From there, the highway goes south through a mostly forested area before passing the west shore of Scotch Bay. Route 172 continues to the community of L'Etang.

The road continues southwest past Browns Cove and Spragues Cove before arriving in the community of Back Bay next to the Bay of Fundy. In Back Bay, the route takes a sharp turn heading west towards the small community of L'Etete. It L'Etele, Route 172 takes a sharp turn south past Matthews Cove and finally the route heads west to the Deer Island Ferry to Deer Island. On Deer Island, the continuation of Route 172 is numbered 772.

Route 172 was commissioned in 2001 as a renumbering of the mainland portion of Route 772, which still exists on Deer Island.