DEFINITION of 'Truck Tonnage Index'
An index that measures the gross tonnage of freight that is transported by motor carriers for a given month. The truck tonnage index serves as an indicator of shipping activity in the U.S., and it can be used by analysts to help determine the state of the economy.
BREAKING DOWN 'Truck Tonnage Index'
The truck tonnage index was first introduced in 1973 by the American Trucking Association. The index is weighted proportionately to reflect the current composition of the trucking industry. There is a one-month lag between the time that the data is compiled and when it is reported.