U.S. retail gasoline prices declined for the ninth week in a row and truckers are enjoying the cheapest diesel fuel in almost four months, the Energy Department (search) said Monday.

The national pump price for regular unleaded gasoline fell 1.3 cents over the last week to $1.778 a gallon. But that was up 27 cents from a year ago, according to a survey of service stations by the Energy Information Administration (search).

Still, it is the lowest price consumers have paid to fill up their tanks since last March.

The EIA, the Energy Department's analytical arm, also said the average price truckers pay for diesel fuel fell 3 cents to $1.957 a gallon, the lowest since mid-September, but up 45 cents from a year ago.

The EIA's weekly survey showed the retail price for cleaner-burning reformulated gasoline (search), sold in polluted metropolitan areas, fell 2.1 cents to $1.848 a gallon.

The drop at the pump mirrors the decline in crude oil prices, which account for about the half the cost of making gasoline and diesel.

Oil futures at the New York Mercantile Exchange (search) fell 3 percent on Monday, settling down $1.33 at $42.12 a barrel.

The West Coast had the most expensive regular unleaded gasoline, with prices down 2.6 cents to $1.93 a gallon. Los Angeles again topped the agency's city survey, with the price of gasoline down 3.3 cents to $1.992 a gallon.

Gulf Coast states had the cheapest fuel, with the price down 3 cents to $1.671 per gallon. Among major U.S. cities, Houston had the best deal at the pump, with fuel down 3.6 cents to $1.631 a gallon.

The weekly report also showed gasoline prices were down 2.6 cents to $1.927 in Miami, down 3.1 cents to $1.88 in New York City, down 2 cents to $1.822 in Seattle, up 1.1 cents to $1.779 in Chicago and up 5 cents to $1.756 in Cleveland.

Truckers in the New England states paid the most for diesel fuel, at $2.18 a gallon, down 1.6 cents from the prior week. The Gulf Coast states had the cheapest diesel at $1.887 a gallon, down 4.1 cents.