As mentioned earlier, trucks move about 78 percent of the nation’s freight. Nation–wide statistics show trucks generally tend to move high–value goods – food products, electronics, live animals, etc. – while rail moves lower–value tonnage, such as coal.
Large truck traffic along major Montana highways varies greatly as a percentage of all vehicles, depending on the section of highway. An automatic station on a remote section of Interstate 15 near the Montana–Idaho border shows fewer than 3,000 annual average daily traffic (AADT), but about 26 percent is large truck traffic. An automatic station along U.S. Highway 2 west of Kalispell, on the other hand, measures almost 9,000 AADT, with only 1.7 percent being large truck traffic. Gallatin Canyon southwest of Bozeman is well known for the influence of truck traffic. A station on U.S. Highway 191 just north of Big Sky measures 5,400 AADT, with 8.5 percent being large trucks.
The U.S. Department of Transportation conducts freight analyses for each state. According to recent figures for Montana, truck traffic moving to and from Montana accounts for about 14 percent of the annual average daily truck traffic (AADTT). Approximately 15 percent of truck traffic involves intra–state shipments. The stretch of Interstate 90 between Billings and the Idaho border carries the greatest amount of truck traffic – about 3,000 AADTT. Most notably, though, 53 percent of measured truck traffic involves containers traveling across the state to other markets.
Montana counties register about 21,000 tractor–trailer trucks, and about 30,000 commercial trailers. Undoubtedly, pass–through traffic from other states would add significantly to these numbers. A more detailed profile of the types of trucks using state highways can be accessed through the Montana vehicle census.
In Montana, trucks hauled more than 22 million tons of freight in 2002 – about 25 percent of all freight by tonnage. Nationally, the average length of a freight trip by truck is about 267 miles. The average number of miles per shipment within Montana was 65 miles. However, a category known as “for–hire” – those who carry freight for a fee from the shipper or the recipient of the shipment – averages about 425 miles in Montana. Of truck shipments that originate in the state, common products by tonnage include sand and gravel, petroleum and fuels, heavy machinery, and cereal grains. As would be expected, products like sand and gravel are not trucked long distances and average about 17 miles. At the other end of the spectrum, livestock averages shipments of about 1,000 miles. Not surprisingly, surrounding states of Wyoming, Washington, Utah, and Idaho originate much of the tonnage trucked into the state. California and Washington originate high–value freight brought into Montana, presumably produce and processed food products.
About 900 fueling stations serve trucks and automobiles in Montana. The state has about 680 truck transportation establishments.
About 220 million gallons of highway-taxed diesel fuel is consumed in Montana per year. While personal vehicle use accounts for some diesel consumption, most is devoted to commercial enterprises and freight. Biodiesel blended fuels are increasing in Montana. More than a million gallons contained some percentage of biodiesel in 2007. About 330,000 gallons of biodiesel was used in the blends, up from 70,000 gallons in 2004.