After months of flirting with record territory, the average national retail price of a gallon of diesel broke through for the week ending Aug. 2 to close at $1.78, the highest price since the U.S. Department of Energy began tracking the average more than a decade ago, according to the Web site www.e-trucker.com/. The record was set in March 2003 during the build-up to the U.S. invasion of Iraq, when prices of crude oil, diesel and gasoline surged. By the end of April, the diesel average was back around $1.50. The current run-up in diesel prices has been more sustained. The national average has been above $1.70 for 16 weeks, with no sign of lower prices on the horizon. Higher prices may, in fact, be on the way. Crude oil futures also set record territory, trading above $44 a barrel in New York Aug. 2. Legal issues with a Russian oil producer, concerns over terrorism and demand have pushed prices to new levels. Diesel prices are now more than 32 cents higher than a year ago. For the week, diesel prices climbed 2.6 cents, but more than that on the East Coast, in the Midwest and along the Gulf Coast. Truckers in the Rocky Mountains and the West Coast saw smaller increases. California drivers are paying $2.115 at the pump, a 42-cent increase over last year. Truckers in the Lower Atlantic region paid the least, with averages around $1.717.