The average price of a gallon of gas fell 25 cents in the past two weeks in the United States, dropping to its lowest level in nearly five-and-a-half years.

Prices for regular-grade gas dropped to $2.47 a gallon in a survey conducted by Lundberg dated Dec. 19, which is down 25 cents since its previous study on Dec. 5.

GasBuddy.com, which also tracks gas prices all over the U.S., says that the national average is even lower, at $2.41 a gallon. The site reported on Friday that gas was less than $2 a gallon in a number of places, but by Sunday the lowest reported price was in Lubbock, Texas, where gas was holding steady at $2.01 a gallon.

The recent drop has lowered prices by more than $1.25 a gallon since the most recent peak in May of earlier this year.

Of 48 states recorded, Long Island had the highest average price at $2.82, and the lowest was the lowest in Tulsa, at $2.06, according to the survey.

American Automobile Association travel analysts said they estimate current gas prices should continue drop, by as much as 7 cents, on Christmas.

Prices could drop an additional drop of 7 cents as early as New Year's Day, according to AAA.

"This is mostly driven by crude oil prices, and absent a sudden spike we very well may see a drop of a few pennies more," said the survey's publisher, Trilby Lundberg, according to Reuters. "That said, demand is up at these low prices."

U.S. crude futures have been a lot weaker lately, dropping for four straight weeks in a row and 11 of the past 12 weeks, according to Reuters.

Crude prices fell 14.2 percent over the past two weeks, though they rose 5.1 percent on Friday, settling at $57.13 per barrel.

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