Federal regulations require a driver to recheck cargo securement during a trip. After the initial check within the first 50 miles of the trip, how often must the driver reexamine the cargo and securement devices?

49 CFR 392.9(b)(2) (initial check within first 50 miles) and 392.9(b)(3) (recheck every 150 miles or 3 hours, whichever occurs first); AAMVA CDL Manual Section 2.1.6, p. 2-7

Cargo that looked secure at the loading dock can loosen once the truck is moving, especially over rough roads or hard braking. These checkpoints exist because shifted or falling cargo causes serious crashes, and missing a required recheck is a citable violation even if nothing goes wrong.