Whether a commercial driver crosses state lines or stays within one state determines which CDL rules and medical requirements apply.

"Interstate" means operating a commercial vehicle in trade, traffic, or transportation that crosses a state border or is part of a trip that does, even if one leg happens entirely inside one state. "Intrastate" means operating only within one state and not as part of interstate commerce. That distinction affects self-certification, medical certification, and which federal or state regulations control the driver and carrier. A common trap is assuming the route alone decides it. It may also depend on the cargo, the employer's business, and where the trip begins or ends.

For drivers, a wrong classification can lead to a downgraded license, out-of-service problems, fines, or denied work. In New Hampshire, the Division of Motor Vehicles requires CDL holders to certify their type of commerce, and interstate drivers often must meet Federal Motor Carrier Safety Administration standards, including a valid medical examiner's certificate. Intrastate drivers may face different state-based limits or exceptions, but "local" does not always mean exempt.

In an injury claim, this split can matter a lot. It helps determine which safety rules applied, whether the driver was properly qualified, and whether a company cut corners. On dangerous New Hampshire routes like I-93 near Franconia Notch, that paperwork issue can become evidence of negligence. New Hampshire's modified comparative fault rule, RSA 507:7-d (1986), also matters: recovery is barred if the injured person is more than 50% at fault.