You are following another vehicle. In New Hampshire, what is the recommended following distance?

The State of New Hampshire Driver's Manual recommends a following distance of at least three seconds behind the vehicle in front of you. You can measure your following distance by noting when the vehicle in front of you passes some stationary object and then counting the seconds that elapse before you reach the same object. If driving conditions are poor, you should increase your following distance. [Following Distance; Part Seven - Following, Passing, and Lane Usage; State of New Hampshire Driver's Manual]