Route 139 is a 32.24-mile-long (51.89 km) west–east state highway in southeastern Massachusetts. Its western terminus is at Route 27 and Route 138 in Stoughton and its eastern terminus is at Route 14 in Duxbury. Along the way it intersects several major highways including Route 24 in Stoughton and Route 3 in Pembroke.

Route 27 is a 73.44-mile-long (118.19 km) south–north state highway in eastern Massachusetts. Its southern terminus is at Route 106 in Kingston and its northern terminus is at Route 4 in Chelmsford. Along the way it intersects several major highways including Route 24 in Brockton, U.S. Route 1 in Walpole, Route 9 in Natick, US 20 in Wayland, and Route 2 in Acton.