What is the difference between an MC number and a US DOT number?

A US DOT number identifies carriers operating in interstate commerce while an MC number identifies a carrier who transports regulated commodities for hire in interstate commerce. Generally, items that have been changed from their natural state are regulated commodities requiring an MC number. Determining whether an MC number versus a US DOT number is required is made by the Federal Motor Carrier Safety Administration, not the ND Highway Patrol.