The average U.S. cost of diesel fell below the $4 a gallon mark for the first time since January.

The weekly roundup from the U.S. Energy Department shows a decline of 1.3 cents over the past week to $3.993 per gallon. This is the fifth straight weekly falloff. Compared to the same week a year ago it’s 14.9 cents per gallon lower.

Regional prices declined in all parts of the country except the West Coast, where it gained 1.5 cents over the past week for an average of $4.116 per gallon, the second highest regional average. New England has the highest regional price at $4.14.8 per gallon, down 2.3 cents from a week ago while the Gulf Coast Region has the least expensive price, $3.915, down 2 cents from a week earlier.

Other regional prices and weekly changes:

• East Coast, made up of the New England, Central Atlantic and Lower Atlantic sub-regions, $4.025, down 2.5 cents.

• Central Atlantic, $4.083, down 2.6 cents.

• Lower Atlantic, $3.958, down 2.5 cents.

• Midwest, $3.97, down 0.9 cents.

• Rocky Mountain, $3.922, down 1.3 cents.

• California, $4.20, up 5.3 cents.

Gasoline also continued its decline in tandem with diesel, falling for the fifth consecutive week, shedding 3.5 cents over the past week for a nationwide average of $3.645 per gallon. Prices range from a high of $3.945 in the West Coast region to a low of $3.48 in the Gulf Coast region. The current overall price is the lowest since around mid-February.

Meantime, oil paused from its run-up over the past week, falling 16 cents by the close of trading Monday in New York, settling at $97.07 per barrel. The decline from its highest price in six weeks came following Exxon closing its Pegasus pipeline from Illinois to the Gulf Coast on March 29 due to a crude leak in Arkansas.

Analysts say a report from the Institute for Supple Management showing U.S. manufacturing in March expanded at a slower rate than the month before led to Monday’s drop.

Compared to a week ago the price of oil is up about a dollar and a half.