New Hampshire Route 107

NH 107 begins at US 1 in Seabrook, just 1.5 miles (2.4 km) north of the Massachusetts state line, and initially travels nearly due west (signed north). The highway interchanges with Interstate 95 0.2 miles (0.3 km) to the west then continues west into the town of Kensington. NH 107 crosses NH 150 and traverses the southern part of Kensington before continuing into East Kingston where it meets NH 108. NH 108 turns onto NH 107, sharing pavement briefly before splitting off to the south. Continuing west into Kingston, NH 107 intersects the northern terminus of NH 107A (its only "child" route) before meeting NH 111 and NH 125. NH 107 turns north onto NH 111 / NH 125, and the three routes overlap for just over 1 mile (1.6 km), then NH 111 splits off to the east. NH 107 continues along NH 125 for another 0.5 miles (0.8 km) before it splits off on its own again.

NH 107 cuts across the southwestern corner of Brentwood, then crosses the Exeter River into Fremont and intersects with NH 111A. The two routes overlap for 1.8 miles (2.9 km) before NH 111A splits off to the south. NH 107 continues along the river until crossing into Raymond. The highway intersects the eastern terminus of NH 102 before turning due north. NH 107 crosses the Lamprey River and interchanges with NH 101 before intersecting with NH 27 east of downtown. NH 107 turns west onto NH 27, and NH 156, a short connector to Nottingham, splits off to the north. NH 27 and NH 107 continue along the Lamprey River for 3.9 miles (6.3 km) before splitting in the western end of town. NH 107 turns north to continue along the Lamprey River into the town of Deerfield, where it intersects with NH 43. NH 43 and NH 107 overlap for 3.5 miles (5.6 km) in Deerfield and split north of the town center. The highway continues northwest into Epsom where it intersects with US 4, US 202 and NH 9 in the eastern end of town. NH 107 turns east to join them, and the four routes run concurrently along the north side of Northwood Lake for 2 miles (3 km), crossing into the town of Northwood along the way. NH 107 splits off and continues northwest into Pittsfield.

NH 107 crosses the town of Pittsfield through windy, hilly terrain before reaching the downtown area. In downtown Pittsfield, the highway turns north and crosses NH 28 before continuing north and crossing into the town of Barnstead. The highway runs briefly through the western corner of the town before continuing northwest into Gilmanton, where it meets the eastern terminus of NH 129, a connector to Loudon to the southwest. NH 107 continues northwest through more hilly terrain for several miles, then crosses NH 140 in the town center. Continuing north, NH 107 traverses the eastern corner of Belmont before entering the city of Laconia.

NH 107 has a partial interchange with the Gilford-Laconia Bypass (US 3 / NH 11); full access is available via NH 106 0.6 miles (0.97 km) to the north. NH 107 joins NH 106 northbound into downtown Laconia via South Main Street. NH 106 and NH 107 intersect with NH 11A (unsigned US 3 Business) in the city's center, near the Winnipesaukee River. NH 107 turns onto NH 11A (Union Avenue) for 0.9 miles (1.4 km), then NH 11A splits off east towards the US 3 / NH 11 bypass. NH 107 (and US 3 Business) continue north on Union Avenue, paralleling Opechee and Paugus bays before reaching its northern terminus at US 3 (Lake Street/Lake Shore Road) at the Laconia/Gilford line (US 3 Business also ends here).