U.S. average retail gasoline prices fell 17 cents per gallon as Midwest refiners recovered from recent difficulties and produced more gas, according to an industry analyst.

The national average for self-serve, regular, unleaded gas was nearly $2.8843 a gallon on July 27, down from the July 13 level of $3.0577, according to the nationwide Lundberg survey of about 7,000 gas stations.

Prices fell after refining capacity in Coffeyville, Kansas and Whiting, Indiana came back online. Trouble at those two sites had pinched supply and lifted prices in the Midwest by about 24 cents a gallon.

Gas prices have tumbled nearly 30 cents a gallon since reaching an all-time U.S. high average on May 18 of $3.1827.

"It's unlikely we'll see a large drop again in average pump prices in the near future," Lundberg said.

Crude oil prices are rising and the summer driving season still has a month to go, both of which should prevent gas prices from falling much further, Lundberg said.

At $3.29 a gallon, Chicago had the highest average price for self-serve regular unleaded gas, while the lowest average price was $2.65 a gallon in Cleveland, Ohio.