The Federal Motor Carrier Safety Administration (FMCSA) in the United States issues commercial motor carriers with DOT numbers as a distinctive identification. The U.S. Department of Transportation’s (DOT) FMCSA section oversees overseeing the safety of commercial motor carriers, such as trucking. The DOT number must be visible on all the carrier’s vehicles to track compliance with federal safety rules.
Another distinctive ID number provided by the FMCSA is an MC number (Motor Carrier number). While a DOT number can be awarded to a carrier that does intrastate business, the MC number is only given to carriers who operate in interstate commerce.
In conclusion, the FMCSA issues both the DOT number and the MC number. Any carrier operating commercial cars in the United States is required to have a DOT number, while any carrier operating commercial vehicles in interstate commerce is required to have an MC number.