U.S. Highway 3

U.S. Route 3
US 3 highlighted in red
Route information
Maintained by MassDOT
Length:	277.90 mi (447.24 km)
Existed:	1926 – present
Major junctions
South end:	Route 2A / Route 3 in Cambridge, MA
	I‑95 / Route 128 / Route 3A in Burlington, MA I‑495 / Lowell Connector in Chelmsford, MA Everett Turnpike in Nashua, NH NH 101 near Manchester, NH US 202 in Concord, NH US 4 near Concord, NH I‑93 in Franconia, NH US 302 in Carroll, NH US 2 in Lancaster, NH
North end:	Route 257 near Chartierville, Quebec
Location
States:	Massachusetts, New Hampshire
Highway system
United States Numbered Highway System List Special Divided Replaced Massachusetts State Highway System Interstate US State New Hampshire Highway System Interstate U.S. State Turnpikes ← Route 2A MA Route 3 → ← US 2 NH NH 3A → ← Route 5 N.E. Route 6A →

U.S. Route 3 Business
Location:	Belmont, New Hampshire–Laconia, New Hampshire
Length:	4.144 mi (6.669 km)

U.S. Route 3 (US 3) is a United States highway running 277.9 miles (447.2 km) from Cambridge, Massachusetts, through New Hampshire, to the Canada–US border near Third Connecticut Lake, where it connects to Quebec Route 257.

In New Hampshire, parts of US 3 are known as the Daniel Webster Highway. From Burlington, Massachusetts, to Nashua, New Hampshire, US 3 is a freeway. The segment in New Hampshire is a free portion of the Everett Turnpike, while the portion in Massachusetts is known as the Northwest Expressway. A second freeway portion exists in northern New Hampshire, where US 3 uses the Franconia Notch Parkway, overlapping Interstate 93.

Massachusetts Route 3 connects to the southern terminus of US 3 in Cambridge and continues south to Cape Cod. Though it shares a number, it has never been part of US 3. Both routes, which connect end-to-end, are treated as a single 91.3-mile (146.9 km) state highway by MassDOT, with mileposts increasing continuously from Cape Cod all the way to the New Hampshire state border. The official end according to AASHTO is at US 20 across the Charles River in Boston, though current signs indicate a terminus in Cambridge at Massachusetts Routes 2A/3.