The streets in downtown Ann Arbor conform to a grid pattern, though this pattern is less common in the surrounding areas. Major roads branch out from the downtown district like spokes on a wheel to the highways surrounding the city. The city is belted by three freeways: I-94, which runs along the southern portion of the city; U.S. Highway 23 (US 23), which primarily runs along the eastern edge of Ann Arbor; and M-14, which runs along the northern edge of the city. Other nearby highways include US 12, M-17, and M-153. Several of the major surface arteries lead to the I-94/M-14 interchange in the west, US 23 in the east, and the city's southern areas. The city also has a system of bike routes and paths and includes the nearly complete Washtenaw County Border-to-Border Trail.

Answer this question, if possible (if impossible, reply "unanswerable"): What is the completed bike trail called?
unanswerable