The FMCSA monitors and ensures compliance with regulations governing both safety (all carriers) and commerce (for-hire carriers). Companies may find they are subject to both registration requirements (U.S. DOT Number and MC Number) or either one separately.
Companies that operate commercial vehicles transporting passengers or hauling cargo in inter-state commerce must be registered with the FMCSA and must have a U.S. DOT Number. Also, commercial intra-state hazardous materials carriers who haul types and quantities requiring a safety permit must register for a U.S. DOT Number.
The U.S. DOT Number serves as a unique identifier when collecting and monitoring a company's safety information acquired during audits, compliance reviews, crash investigations, and inspections.