What are the differences between an interstate and intrastate carrier?

Interstate and Intrastate authority mainly describes where a trucking company will operate. Interstate commerce is transportation involving the crossing of any state boundary. It does not matter how many state borders you plan to cross with your trucking company, as soon as you cross one, you are considered an interstate trucking company. Since interstate authority involves the legal jurisdictions of multiple states, your authority requirements increase when you choose to operate across state lines. 

Intrastate commerce is transportation entirely within the boundaries of a single state. Because you are only subject to a single state’s laws and regulations, intrastate carriers are subject to far fewer authority requirements from the FMCSA. Please note that a carrier who does both intrastate and interstate commerce is classified as an interstate carrier for purposes of authority requirements with the FMCSA.