A global glut of oil has pushed the national price of gasoline to $3.39 and plunging. In certain places, such as Greene County, Missouri, unleaded already goes for under $3.

“At this moment today, we are at $2.95,” says James Orr, manager of Casey’s General Store on South Grant Avenue in Springfield, the county seat. As for his competitors, “most of them are at $2.98, $2.99.”

A few factors are at play here: As of this week, gas stations in many states can sell a cheaper gasoline product called winter blend. Summer blend gas is held to a stricter standard, for warm-weather pollution reasons.

In world oil markets, where pump prices are mostly set, there is ample supply. A big factor in that is rising U.S. production, now at a 28-year high. Finally, global demand has softened in places like China.

Houston-area oil industry consultant Andy Lipow thinks the national gas price will fall another seven percent to $3.15 by Halloween.

“And $3 a gallon is in the cards if we can see crude oil prices decline to $85 a barrel,” Lipow says.

A year ago, the president and CEO of the auto club AAA, Robert Darbelnet, predicted $3 a gallon gas would never return.

“Paying less than $3 per gallon for gasoline may be automotive history for most Americans, like using 8-track tapes or going to a drive-in movie,” Darbelnet said in September 2013. “The reality is that expensive gas is here to stay, which is tough on millions of people who need a car to live their lives.”

A spokesman for AAA said Darbelnet was unavailable for an interview. The group’s current gas price prediction is that winter prices will dip to $3.10.