Nashua until Exit 7, then runs by itself north to Manchester, where it interchanges with I-293 and NH 101. The Everett Turnpike is cosigned with I-293 from the NH 101 interchange north to I-93 in Hooksett, then has an unsigned concurrency with I-93 to its northern terminus in Concord at Exit 14 (NH 9). The Eastern Turnpike is composed of the following two connecting turnpikes: The Blue Star Turnpike (unsigned; also known as the New Hampshire Turnpike) runs from the Massachusetts border in Seabrook north to the Portsmouth Traffic Circle, where it connects with the southern end of the Spaulding Turnpike. The Blue Star Turnpike is signed solely as I-95 and comprises most of its length in New Hampshire. The Spaulding Turnpike, which begins at an interchange with I-95 in Portsmouth and runs northward, paralleling the Maine state line, to Milton. Originally a standalone route, NH 16 is now overlapped with all but the southernmost of the Spaulding Turnpike. US 4 also runs along the southern section of the turnpike, between I-95 and exit 6. National Highway System of state-maintained roads are a part of the National Highway System (NHS). Of the NHS roads in the state, are Interstate highways ( of which are also on the New Hampshire Turnpike System); are non-interstate turnpike highways; and are non-interstate and non-turnpike highways. Classification of state highways New Hampshire RSA 229:5, "Classification", sets out the seven different classes of highways in the state: Class I – all portions of the turnpikes and the national system of interstate and defense highways, and all existing or proposed highways on the primary state highway system, excepting all portions of highways within the compact sections of the cities and towns listed in RSA 229:5, V., which aren't part of the state or national turnpike system or are defense highways Class II – all existing or proposed highways on the secondary state highway system, excepting all portions of such highways within the compact sections of the cities and towns listed in RSA 229:5, V. Class III – all recreational roads leading to, and within, state reservations designated by the General Court Class III-a – boating access highways from any existing highway to any public water in this state. Class IV – all highways within the compact sections of cities and towns listed in RSA 229:5, V., which are not Class I or II highways Class V –