The average price U.S. drivers pay for gasoline fell below $1.90 a gallon for the first time in nine weeks, but crude oil costs are on the rise, the government said Tuesday.

The national price for motor fuel dropped 2.6 cents a gallon over the last week to $1.895, the lowest since May 3 and the sixth week in a row that gasoline costs have fallen, according to the Energy Information Administration's (search) weekly survey of service stations.

The Energy Department's (search) analytical arm said pump prices are still 41 cents a gallon higher than a year ago.

The drop in gasoline prices may slow or even halt temporarily if crude oil prices continue to rise. Oil accounts for about half the cost of making gasoline.

Oil for delivery in August rose $1.26 to $39.65 a barrel on Tuesday at the New York Mercantile Exchange (search), the highest level since early June, on supply fears after a halt in Nigerian oil production and sabotage disrupted Iraq's crude exports.

The EIA's weekly report also showed the retail price for cleaner-burning reformulated gasoline, sold in polluted metropolitan areas, declined 2.9 cents to $2.02 a gallon.

The West Coast had the most expensive regular unleaded gasoline, with the price down 3.9 cents to $2.136 a gallon. San Francisco again topped the agency's city survey of gasoline costs, but the price fell 3 cents to $2.24 a gallon.

The U.S. Gulf Coast had the cheapest fuel by region, with the price down 2.5 cents at $1.784 per gallon. Houston had the lowest pump price at $1.739 a gallon, down 3.9 cents.

The weekly report also showed gasoline prices were down 2.5 cents to $2.05 in New York City, down 6.5 cents to $2.044 in Seattle, down 2.7 cents to $1.983 in Miami, down 1.8 cents to $1.918 in Chicago, and up 3.3 cents to $1.816 in Cleveland.

Separately, the EIA survey said the average pump price for diesel fuel increased 1.6 cents to $1.716 a gallon, up 29 cents from a year earlier.

Truckers on the West Coast paid the most for diesel fuel at $2.01 a gallon, up 4.1 cents from the prior week. The Gulf Coast states had the cheapest diesel at $1.641, up 1.7 cents.