At $4.999, diesel prices have declined 82 cents since hitting a record high of $5.82 on June 19.
Gasoline prices also continue to drop.
The national average for regular gas fell to $3.93 a gallon Thursday, according to AAA. That marks the 65th consecutive day of declining prices since gas hit a record high of $5.02 in mid-June. Prices in 14 states, including Florida and Iowa, are averaging less than $3.60 a gallon.