FMCSA stands for the Federal Motor Carrier Safety Administration. It’s the branch of the US Department of Transportation focused on reducing crashes, injuries, and deaths involving large trucks and buses, through safety regulations and the systems that track carrier compliance.
A lot of everyday trucking rules trace back to the FMCSA — from Hours of Service limits to the authority a carrier operates under. It issues the MC Number and works alongside the USDOT registration that identifies commercial operators.