Massachusetts Route 4

Route 4
Route 4 highlighted in red
Route information
Maintained by MassDOT
Length	18.2619 mi[1] (29.3897 km)
Existed	ca. 1930–present
Major junctions
South end	Route 2 in Lexington
Major intersections	I-95 / Route 128 in Lexington I-495 / US 3 in Chelmsford
North end	Route 3A in North Chelmsford
Location
Country	United States
State	Massachusetts
Counties	Middlesex
Highway system
Massachusetts State Highway System Interstate US State
← Route 3B → US 5

Route 4 is an 18.26-mile-long (29.39 km) state highway in northeastern Massachusetts. It runs south to north, serving many of Boston's western and northwestern suburbs, from an interchange with Route 2 in Lexington northwest to an intersection with Route 3A in North Chelmsford. Much of it, north of Lexington, runs parallel to U.S. Route 3 (the Northwest Expressway). The entire route is contained within Middlesex County.