WOODBRIDGE, N.J. -- Stock prices aren't the only thing fluctuating. The cost of fuel is as well. Oil closed below $40 a barrel for the first time since the Great Recession. Gasoline has fallen to a nationwide average of $2.59 a gallon. And in some places, it's a lot lower than that.

Filling up at a Woodbridge, New Jersey, gas station is like taking a drive back to 2009 -- that's the last time a gallon of gas was below $2 a gallon.

According to AAA, 12 states have at least one station selling gas for less than $2 a gallon.

A map showing the states where gas is being sold for less than $2 a gallon CBS News

Oil analyst Denton Cinquegrana says one reason for the low prices is the increase in U.S. oil production.

"U.S. production is at levels not seen since the early 70s," said Cinquegrana. "OPEC continues to produce at a very high level and now there's major concern about Chinese demand, which has been a driver for the past decade."

On the West Coast and in parts of the Midwest they're paying almost a dollar-and-a-half more than drivers in New Jersey.

Gas is more expensive in places like California partly because of production problems at refineries on the West Coast. But, on average, American households have saved at least $530 on gas so far this year.