June 9 (Reuters) - The average price of a gallon of gasoline in the United States slipped less than 2 cents over the past three weeks, but some cities saw swings of as much as 50 cents, according to a widely followed survey released on Sunday.
The average price for a gallon of gasoline slipped 1.81 cents to $3.6385 on June 7, according to the Lundberg Survey of about 2,500 gas stations across the country. The previous survey found the average price on May 17 was $3.6566 per gallon.
The slight change in the average masked signifcant price drops in some cites in the West and near the Gulf of Mexico as well as sharp rises in some parts of the Midwest, said Trilby Lundberg, the author of the survey. The differences stemmed from differences in refinery capacity as work was completed on some of the facilities while continuing on others, she said.
The price per gallon in Minneapolis, for example, fell nearly 51 cents, while the price in Chicago rose nearly 24 cents, the survey found.
"It is very much a situation of happenstance," Lundberg said.
The Chicago price, which includes some of the highest taxes in the nation, was $4.48 a gallon and the highest found by the survey. Drivers in Jackson, Mississippi, paid the least per gallon at $3.20.
Crude oil prices were essentially unchanged during the period and are putting no particular pressure on future gasoline prices, she said.
The profit margin for gasoline retailers, however, was less than 11 cents a gallon, down from about 14 to 18 cents during much of the spring. "We might see some very modest price rises in the future because retailers need to recovery their margins," Lundberg said.