U.S. retail gasoline prices fell to their lowest level since early May, dropping 1.7 cents over the last week to $1.888 a gallon, the government said Monday.

But the average price for regular unleaded gasoline is up 35 cents from a year ago, according to the Energy Information Administration's (search) weekly survey of service stations.

The drop in pump prices may slow or even reverse in coming weeks as higher crude oil costs could be passed through the marketing system to consumers.

Crude oil for delivery in September settled up 2 cents at $43.82 a barrel on Monday at the New York Mercantile Exchange (search) after hitting a NYMEX record high of $43.94 earlier in the day.

The price for oil accounts for almost half the cost of making gasoline.

The EIA's weekly report also showed the retail price for cleaner-burning reformulated gasoline, sold in polluted metropolitan areas, fell 2.1 cents to $1.975 a gallon.

The West Coast had the most expensive regular unleaded gasoline, with the price down 2.9 cents to $2.062 a gallon. San Francisco topped the agency's city survey of gasoline costs, but the price fell 1.1 cents to $2.161 a gallon.

The U.S. Gulf Coast (search) had the cheapest fuel by region, with the price down 1.6 cents at $1.79 per gallon. Houston had the lowest pump price at $1.746 a gallon, down 1.8 cents.

The weekly report also showed gasoline prices were down 1.6 cent to $2.002 in New York City, down 1.8 cents to $1.935 in Seattle, down 2.5 cents to $1.912 in Chicago, down 6.9 cents to $1.905 in Miami, and up half a penny to $1.839 in Cleveland.

Separately, the EIA survey said the average pump price for diesel fuel increased 2.6 cents to $1.78 a gallon, up 33 cents from a year earlier.

Truckers on the West Coast paid the most for diesel fuel at $2.036 a gallon, up half a penny from the prior week. The lower Atlantic states had the cheapest diesel at $1.717, up 2.8 cents.