For the first time since late April, the average price of gasoline is higher than it was a year ago.

Drivers are now paying an average of $3.66 per gallon, a penny more than on this day last year. The last time gas that happened was April 23, according to auto club AAA. Gas is up 10 percent from July 1 and experts say pump prices could keep rising through Labor Day.

Some drivers, like those in the Midwest and on the West Coast, are feeling a bigger pinch. Prices spiked about 40 cents per gallon last week in parts of Wisconsin, Michigan and Illinois because of refinery and pipeline problems. This week, drivers in California, Oregon and Washington are watching pump prices jump after a partial outage at a big Chevron refinery.

Gas prices had already been steadily advancing across the country in line with an increase in oil.

In all on Thursday, 19 states have average prices above what they were on this date a year ago, according to Tom Kloza, chief oil analyst at the Oil Price Information Service. He sees more increases ahead.

"Trends indicate that more than half of the country may see year-on-year increases" by mid-August, Kloza said.

Kloza does expect nationwide gas prices to fall after Labor Day. In many cities prices should drop below $3.50, while in a few cities gas could fall below $3 per gallon, he said.

Californians, however, will be happy if gas stays below $4. Chevron Corp. is producing gasoline and other fuels at a reduced capacity at its oil refinery near San Francisco after a fire Monday. The refinery was producing about 16 percent of the West Coast's daily gasoline consumption, Kloza said.

Some California cities could see $4 gas, but prices should stabilize without additional refinery problems, Kloza said. Average gas prices in California were $3.9274 per gallon Thursday, up 7.4 cents since Monday, AAA spokesman Michael Green said

Analysts believe other refineries could make up some of Chevron's lost production, helping to curb price hikes.

Meanwhile, oil prices were flat after China said factory production grew at a slower pace in July and retail sales weakened. That's renewing expectations for government action to boost the world's second-biggest economy.

Benchmark oil rose 1 cent to $93.36 per barrel in New York. Brent crude, which is used to price international varieties of oil, gained $1.08 to $113.22 per barrel in London.

Other futures prices on the New York Mercantile Exchange:

— Natural gas prices rose after a government report showed a smaller than expected increase in U.S. inventories. Futures rose 1.2 cents to $2.945 per 1,000 cubic feet, although they had gained more than 10 cents earlier.

— Heating oil increased 2.91 cents to $3.045 per gallon.

— Gasoline gained 2 cents to $3.00 per gallon.