MC# stands for Motor Carrier Number. An MC# is assigned by the FMCSA to carriers, brokers, and freight forwarders who have registered and been authorized to operate in interstate commerce. For an MC# to remain active, the entity must maintain the proper levels of insurance or surety bond and keep that information current with the FMCSA. Tip: Getloaded can assist you in applying for your authority and state permits. Call GLAuthority.com today at 866-265-3172 or visit GLAuthority.com