The National Tank Truck Carriers, Inc. (NTTC) is a trade association composed of over 240 trucking companies that specialize in bulk transportation services by cargo tank throughout North America.  Additionally, NTTC has over 350 associate members that service the bulk transportation industry including cargo tank repair facilities, tractor manufacturers, tank trailer manufacturers, and other related tank truck equipment and services.  The tank truck industry generates roughly 5.1% of all truck freight revenue, but that represents 25.6% of all truck freight in terms of tonnage due to the heavy nature of the liquid bulk products handled.