Massachussets Route 40 has three major intersectionslocated in Groton and two in Chelmsford.
Route 40 is a 10.46-mile-long (16.83 km) eastwest state route located in northeastern Massachusetts, entirely within Middlesex County. The short highway connects Groton and Chelmsford. Its western end is at an intersection with Massachusetts Route 119 and Massachusetts Route 225 in Groton, and its eastern end is at Route 3A in North Chelmsford. Route 40 begins in the west near the center of Groton at an intersection with Main Street (Routes 119 and 225). Route 40 continues another mile eastward, emerging from the woods before ending at an intersection with Route 3A in the center of North Chelmsford at Vinal Square, located just west of the Merrimack River. 
