ESTIMATING STATE-LEVEL TRUCK ACTIVITIES IN AMERICA

For freight, the primary function of the nation's highway system is to link the economies of individual states together to form an integrated national economy. Data from the 1993 Commodity Flow Survey, the first comprehensive national survey of freight shipments since 1977, indicate that the shipment of freight by truck in the United States is predominantly an interstate phenomenon. In fact, interstate shipments comprise more than 70% of the total ton-miles and nearly 55% of the value of the commodities shipped by truck in 1993. In addition, the proportions of truck freight shipments originating from, destined to, passing through, or occurring entirely within a state very significantly from state to state. While interstate shipments make up the largest portion of shipments nationally, intrastate trucking is more significant in large states such as Texas and California, as well as in corner states such as Florida, Maine, and Washington. The proportion of through traffic also varies from state to state. These findings could have important implications for highway revenue allocations, since trucks carrying freight play a significant role in damage to highway pavement and structures