Route 640 is a 35.9-kilometre (22.3 mi) long mostly north–south secondary highway in the southwestern portion of New Brunswick, Canada. Most of the route is in Prince William Parish. The route starts at Route 102 in Fredericton where it is known as Hanwell Road. It passes and travels southwest to exit 3 on Route 8. The road then travels across Route 2 at exit 281 as it enters Hanwell. The route passes The Hanwell Recreational Park. Mazzerolle Settlement Road provides access between Route 640 and Route 2 (at exit 271) and access to Kingsclear. The route passes Yoho Lake as it enters , and it then crosses a branch of before entering . From there, the route passes the northern terminus of Route 645 before ending in at Route 3.