(CNN) -- U.S. gasoline prices have held steady over the past two weeks and could soon drop due to lagging demand, the latest Lundberg Survey found.
The nationwide average price of a gallon of self-serve regular slipped down a fraction of a penny, holding at just under $3.61, survey publisher Trilby Lundberg told CNN. Crude oil prices have remained steady, while Hurricane Irene has had little impact on refineries along the East Coast, she said.
But by grounding flights and keeping residents hunkered down, Irene and lingering high unemployment has put a big enough dent in demand for fuel that prices are likely to fall in the next two weeks, Lundberg said.
"It's a non-story for supply. It's a big story for demand," she said.
But gas prices remain an average of 91 cents per gallon more than they did a year ago. And underneath the stable national average were regional shifts, with prices dipping in the eastern and Gulf states and increasing in the West and Midwest, she said.
The Lundberg Survey tracks prices at about 2,500 filling stations across the United States, most recently on August 26. The highest average price found was in Chicago, at $4.02 per gallon; the lowest was in Tucson, Arizona, at $3.26.
Average per-gallon prices in other cities:
Billings, Montana: $3.62
Newark, New Jersey: $3.44
Salt Lake City: $3.50
San Francisco: $3.77