The route starts in
Hudson at
Route 111 (Ferry Street) and
Route 3A (Chase Street). This starts a concurrency with Route 3A. The southern part of this concurrency forms one of the main commercial districts in Hudson, known as Derry Street. At Elm Avenue, 3A leaves the concurrency heading west, while 102 continues in a more northeasterly direction along Derry Road. After passing
Alvirne High School, NH 102 passes through the extreme southeastern corner of
Litchfield before returning to Hudson. After leaving Hudson a second time, it enters
Londonderry as Nashua Road, passing through a rural area near several farms and apple orchards. A small commercial district surrounds the intersection with
New Hampshire Route 128/
Mammoth Road, and another more developed commercial district lies just to the west of 102's interchange with
I-93. Immediately after the interchange with I-93, Route 102 enters
Derry as Broadway, the main commercial thoroughfare in town. After the intersection with Crystal Avenue (
New Hampshire Route 28) at the center of town, it passes the Hoodkroft golf course and meets Main Street (
New Hampshire Route 28 Bypass) at a traffic circle at the community of Derry Village. After the traffic circle, the route continues northwest along Chester Road, passing the Beaver Lake recreational area, and winding through the rural eastern portion of the town of Derry before entering the town of
Chester, forming the main north-south route through the town. At the town center of Chester, NH 102 intersects
New Hampshire Route 121, following Derry Road south of the intersection, and Raymond Road north of the intersection. Following a more northeasterly route, it winds through a rural area in southeastern
Raymond before reaching its eastern terminus at
New Hampshire Route 107, about short of the interchange with the
New Hampshire Route 101 freeway. ==Major intersections==