An MC Number (Motor Carrier Number) is the operating-authority credential the FMCSA grants to a carrier, showing it’s authorized to move regulated freight across state lines for hire. It’s often used alongside — but is distinct from — the USDOT number.
Brokers and shippers check a carrier’s MC Number to confirm it holds active authority before trusting it with a load. Verifying it is part of qualifying an authorized carrier and guarding against fraud.