Speed & Conditions
Posted limits are set for ideal conditions. New Hampshire's 'reasonable and prudent' Basic Speed Law also requires you to slow down when traffic, weather, or the road makes the posted limit unsafe.
Speed limits
New Hampshire posts 65 mph on most rural interstates, with a section of Interstate 93 north of Concord posted at 70 mph, and lower limits elsewhere and in towns. Always obey the posted signs, which may be lower than the maximum.
Basic Speed Law
Never drive faster than is reasonable and prudent for current conditions, even when that speed is below the posted limit. Adjust for traffic, weather, curves, and visibility.
Winter and mountain driving
Snow and ice greatly increase stopping distance on New Hampshire's hills and mountain passes, so slow down, leave extra space, and avoid cruise control. When entering an interstate, use the ramp to match traffic speed and merge into an open gap.