Dawson said she's cut her speed by five to 10 miles per hour to save money for her company. Many independent owner-operators have slowed even more, she said.
"My fiance is an owner-operator and he's been crying a lot about the price of fuel," Dawson said. "He's been slowing way down."
Truckers and industry officials say slowing a tractor-trailer rig from 75 mph to 65 mph increases fuel mileage by more than a mile a gallon, a significant bump for machines that get less than 10 miles per gallon hauling thousands of pounds of freight. Even sitting still with the engine idling, a rig gulps about a gallon of diesel every hour.
"We just can't afford it," Dawson said of diesel as she was topping off her fuel tanks at a Bismarck truck stop.
When she started driving trucks in 1997, diesel was about $1.97 a gallon, $2 a gallon cheaper than what she paid Wednesday in Bismarck. Rigs like hers have two fuel tanks, typically holding 300 gallons each.
The nationwide average for a gallon of diesel on Thursday was $4.03, up from $2.74 one year earlier, AAA North Dakota spokesman Gene LaDoucer said. The average in North Dakota on Thursday was $3.98, up from $2.82 a year ago, he said.
"Twenty-four states are paying $4 or higher," LaDoucer said Thursday.
The climb is blamed on record crude oil prices and global demand, LaDoucer said.
"Diesel is the predominate fuel used in foreign countries, and there is a lot more demand for it globally and that helps bid up the price that we are paying here," LaDoucer said.
Fuel accounts for about a quarter of carriers' operating costs, and now is surpassing labor as the biggest expense for some carriers, said Tiffany Wlazlowski, a spokeswoman for the Arlington, Va.-based American Trucking Associations.
"And rising fuel costs do increase the cost of consumer goods," she said.
Trucks haul 70 percent of all freight tonnage in the U.S., according to the American Trucking Associations.
State troopers have noticed the decline in truckers' speeds, said North Dakota Highway Patrol Capt. Eric Pederson.
"We see it when we're out patrolling," Pederson said. "In talking to the drivers, a lot of the large companies are setting policies that give the drivers a little more leeway on the time on their loads - just to save on the fuel."
Wlazlowski said the U.S trucking industry expects to spend $135 billion on diesel this year, up from $112 billion in 2007. There are 3.5 million truck drivers in this country, she said.
"For every one-penny increase in the price of diesel, it costs our industry $391 million," she said. "In the last month, it's gone up 50 cents."
Wlazlowski said the trucking industry does "anything that will help them save fuel." She said that includes outfitting trucks with aerodynamic fairings and special tires to improve mileage. Drivers also are using more efficient routes and reducing idling times.
Trucking company Con-way Inc. of Ann Arbor, Mich., announced this month that it adjusted speed governors on the engines of the 8,400 semis in its less-than-truckload division, Con-way Freight.
Truckload carriers usually dedicate a shipment to a single customer, and move freight directly from the shipper to the receiver. Less-than-truckload carriers are filled with shipments from multiple customers, and may redistribute it at terminals along routes.
Con-way spokesman Gary Frantz said the maximum speed of the trucks has been cut from 65 mph to 62, a move that should cut fuel consumption by 3.2 million gallons a year.
"It's a significant savings," Frantz said.
The company said the move also would eliminate 72 million pounds of carbon emissions annually, or the equivalent to removing nearly 7,300 automobiles from U.S. highways.
Frantz said the company should have the governors on the 3,000 rigs in its truckload fleet adjusted next month.