Route 121A runs north to south through the center of Plaistow, as a local route. It crosses NH 125 north of the center of town and rejoins 125 at the south end of town, at the Massachusetts border. NH 121A leads north through Hampstead and Sandown to Chester. New Hampshire Route 108 runs north to south along the eastern edge of Plaistow, just west of the Massachusetts border. Route 108 leads north to Newton and Exeter and south to the center of Haverhill.