The length of haul on full truckload shipments within the US has been shifting downwards for years. The trend became particularly clear to me during some freight bids with which I was involved last year. During the course of these bids, a number of the major US national truckload carriers outlined their companies' regional truckload strategies and were very clear about their objective to build their regional businesses.
The move from national (e.g. greater than 500 miles) to regional truckload shipping (e.g. less than 500 miles) was precipitated by a number of factors. The freight recession that began in 2006 has resulted in fewer longhaul truckload shipments. As fuel costs began to increase, it became very punishing financially to incur out-of-route miles to chase backhaul freight, particularly when these miles were not all producing revenue. In addition, the intermodal option became more attractive on longer distances, when you consider line-haul and fuel costs. As fuel costs were escalating, supply chain managers sought to shorten their supply chain to reduce miles, inventory costs and freight costs.