For some Ottawa residents, saving 20 to 30 cents on a gallon of gas is worth planning an entire day around.

“I go out of my way all the time to go to Peru,” Alina Maxson of Ottawa said, adding that she regularly bypasses closer stations for cheaper fuel off Interstate 80.

Chelsea Greer, also of Ottawa, said she doesn’t usually leave town just for gas, but she adjusts when it fits her schedule.

“If I’m already out shopping, I’ll plan my day around getting it where it’s cheaper,” she said.

Regular gas can be found cheapest for $2.69 a gallon at stations on the west side of La Salle County. Meanwhile, the lowest price goes up to $2.89 in Ottawa and Streator, according to GasBuddy.com.

That 20-cent difference is actually significantly smaller than it has been in recent months. In October, the gap reached 80 cents, with prices around $2.59 in La Salle, Peru, Oglesby, Tonica and Utica compared with $3.19 in Ottawa and Streator.

So why do west-side towns consistently come in cheaper?

Rick Pretsch, an economics professor at Illinois Valley Community College, said the biggest factors aren’t competition or daily price movements, they’re a combination of local taxes, transportation costs and property tax differences between communities.

“A lot of the difference between towns simply comes down to local taxes – city, county or even property taxes,” he said. “Stations in lower-tax areas may have more room to charge less at the pump.”

The statewide average for unleaded is $3.13 a gallon, with La Salle County’s average being $2.90. LaSalle County is considered one of the cheapest counties in Illinois, and that trend is down from previous weeks and months.

Pretsch said the broader market also is working in drivers’ favor this year.

“We peaked out in September with very large oil production in the United States,” he said. “OPEC+ has increased output as well, while major economies are slowing down. Manufacturing and trucking, two of the biggest consumers of fuel, have both decreased.”

OPEC+ is a coalition of countries that work together to manage global supply. The result of this is an unusual combination: higher supply and lower demand.

“Right now, we’re actually fortunate,” Pretsch said. “There’s an increase in oil production but a decrease in demand, and that helps keep prices down.”

Competition among gas stations also plays a role, with Peru Mayor Ken Kolowski believing that makes the difference.

“Competition brings prices and inflation down. Our Quiktrip up on [Interstate] 80 sets the tone for the gas prices in Peru,” Kolowski said.

Quik Trip could not comment on its gas prices, per company policy.

Seasonal patterns also play a role, as winter is here. While summer travel typically pushes prices higher, the holiday season also brings a lot of driving, although not enough to offset current market trends.

Pretsch noted that Illinois has another advantage many residents don’t realize.

“We’re the fourth-largest state for oil refining, right behind Texas, Louisiana and California,” he said. “We don’t produce a lot of oil here, but having refining capacity closer to home helps keep costs lower than people might expect.”

Even so, he said, the local differences across La Salle County almost always come down to the basics: taxes, delivery costs and the financial realities of each station.

“Some towns simply have a lower tax burden,” Pretsch said. “And that can make all the difference at the pump.”