Route 3A | ||||
|---|---|---|---|---|
 Route 3A highlighted in red | ||||
| Route information | ||||
| Maintained by MassDOT | ||||
| Length | 97 mi[1] (156 km) | |||
| Existed | 1926–present | |||
| Southern section | ||||
| Length | 53.392 mi[1] (85.926 km) | |||
| South end |  Route 3 in Plymouth | |||
| Major intersections |  US 44 in Plymouth Route 53 in Kingston Route 53 in Quincy | |||
| North end |    I-93 / US 1 / Route 3 / Route 203 in Boston | |||
| Northern section | ||||
| Length | 22.5043 mi[1] (36.2172 km) | |||
| South end |    I-95 / US 3 / Route 128 in Burlington | |||
| Major intersections | Lowell Connector in Lowell Route 110 in Lowell Route 113 in Tyngsborough | |||
| North end |  NH 3A in Hudson, NH | |||
| Location | ||||
| Country | United States | |||
| State | Massachusetts | |||
| Counties | Plymouth, Norfolk, Suffolk, Middlesex | |||
| Highway system | ||||
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Route 3A is a 97-mile-long (156 km) state highway in eastern Massachusetts, which parallels Route 3 and U.S. Route 3 from Cedarville in southern Plymouth to Tyngsborough at the New Hampshire state line.
Route 3A has two major posted segments, separated by a lengthy concurrency with Route 3 and US 3. Its southern portion parallels Route 3 from Cedarville in southern Plymouth to Neponset in the Dorchester area of Boston. Towns and cities that Route 3A traverse along its path include Plymouth, Kingston, Duxbury, Marshfield, Scituate, Cohasset, Hingham, Weymouth and Quincy.
North of Neponset, Route 3A runs, unsigned, concurrently with Route 3 and U.S. Route 3 to Burlington, before separating again (MassDOT counts the mileage along MA 3 between the two sections as part of MA 3A mileage).
The northern portion of Route 3A parallels U.S. Route 3 in northwestern Middlesex County. It stretches from Interstate 95 (Route 128) in Burlington to the New Hampshire state line, where it continues as Route 3A.