New Hampshire Route 128 (abbreviated NH 128) is a 16.059-mile-long (25.844 km) north–south highway in southeastern New Hampshire. NH 128 runs from the Massachusetts border in Pelham northward to Londonderry, south of Manchester. NH 128 is named Mammoth Road throughout its entire length.

New Hampshire Route 128
Map of southern New Hampshire with NH 128 highlighted in red
Route information
Maintained by NHDOT
Length	16.059 mi[1] (25.844 km)
Major junctions
South end	Mammoth Road in Dracut, MA
Major intersections	NH 111 in Windham NH 102 in Londonderry
North end	NH 28 in Londonderry
Location
Country	United States
State	New Hampshire
Counties	Hillsborough, Rockingham
Highway system
New Hampshire Highway System Interstate US State Turnpikes
← NH 127 → NH 129

The southern terminus of NH 128 is at the Massachusetts state line in the town of Pelham, where the road continues into Massachusetts as an unnumbered road in the town of Dracut. The road, however, is still named Mammoth Road in Dracut. The northern terminus is at New Hampshire Route 28 in Londonderry. Mammoth Road continues northward along NH 28 and then New Hampshire Route 28A.