Route 2 splits off as a freeway to the west (Concord Turnpike), while US 3 and Route 16 stay on the Alewife Brook Parkway. Shortly thereafter, US 3 splits from the parkway (which continues as Route 16) and joins Route 2A (Massachusetts Avenue) westbound, crossing into Arlington. In the center of town, US 3 and Route 2A split from Massachusetts Avenue and overlap briefly with Route 60 before continuing along Mystic Street. Route 2A splits from US 3 just to the north. US 3 continues through parts of Winchester and Woburn without any major intersections before entering Burlington and interchanging with I-95 and Route 128 (Yankee Division Highway) at exit 51A. US 3 joins the freeway to connect with the Northwest Expressway, while its historic surface alignment continues as Route 3A. Burlington to Tyngsborough (Northwest Expressway) US 3 runs along of I-95 (Route 128) in a wrong-way concurrency before exiting at exit 50A onto its own freeway, the Northwest Expressway. Originally built in the 1950s, before the cancelation of the Inner Belt, the US 3 freeway was to have extended into metro Boston before being truncated to I-95. Consequently, a partially completed cloverleaf interchange connects US 3 to I-95. Exit numbers on the US 3 freeway start at milemarker 72 since Route 3 and US 3 are counted as one highway by MassDOT. The freeway closely parallels Route 3A, the historic alignment of US 3, along its entire length from Burlington to the New Hampshire state border. It passes through Billerica and into Chelmsford, where it connects with I-495 and the Lowell Connector, a freeway spur into downtown Lowell. Continuing north, the freeway briefly enters Lowell, then passes through North Chelmsford and Tyngsborough before crossing the state line into Nashua, New Hampshire. The freeway continues north as the Everett Turnpike. The Burlington to Tyngsborough area maintains a 501(c)6 nonprofit representative entity known as the Middlesex 3 Coalition and its affiliate agency the Middlesex 3 TMA, which provides collaborative support to businesses and individuals within the jurisdiction to build consensus on transportation and developmental needs. New Hampshire US 3 passes through most of the state's major cities and towns and is the only highway to extend from the Massachusetts state border in the south to the Canada–US border in the north. Running for in New Hampshire, US 3 is by far the longest signed highway in the state. For much of