WASHINGTON, D.C. --- The U.S. average retail price for regular gasoline increased for the 10th straight week, according to an Energy Department report released June 4. Although the price's upward momentum slowed, the U.S. average price still climbed another 3.9 cents to hit $3.976 per gallon.

The average price for the East Coast went up 3.3 cents to $3.97 per gallon. Meanwhile, prices in the Central Atlantic and New England increased by more than 5 cents, climbing past the $4 mark to reach $4.001 and $4.028 per gallon, respectively, according to the department's Energy Information Administration (EIA).

The average price in the Midwest was essentially unchanged, creeping up by only a tenth of a cent to $3.952 per gallon. The average price in the Gulf Coast increased by 1.7 cents to $3.846 per gallon and remained the lowest of any region.

The price in the Rocky Mountain region went up 3.9 cents to $3.89 per gallon. The price for the West Coast extended its upward surge, jumping another 13.7 cents to strike $4.166 per gallon. West Coast prices have risen 28.3 cents over the past two weeks. The average price in California went up even more, shooting to $4.242 per gallon, an increase of 14.3 cents from the previous week, the EIA said.

For the first time since May 5, the national average diesel price faltered in its upward climb, slipping by 1.6 cents to $4.707 per gallon. Diesel prices dipped somewhat in most regions of the country.

The average diesel price on the East Coast dropped 2 cents to $4.759 per gallon. However, in New England, the diesel price went up slightly, gaining three-tenths of a cent to reach $4.846 per gallon. In the Midwest, the price went down the most of any region, by only 2.4 cents to $4.643 per gallon. The average diesel price in the Gulf Coast was $4.664 per gallon, a decrease of nine-tenths of a cent.

Contrary to what was happening in the other major regions, the diesel price in the Rocky Mountains increased, growing by 2.7 cents to hit $4.68 per gallon. On the West Coast, the average diesel price slipped by half a cent to $4.878 per gallon. The average diesel price in California was unchanged at $5.027 per gallon, reflecting an increase of $2.055 above the price one year ago, the EIA reported.