The average national price of unleaded regular gasoline is poised to fall below the $2 per gallon threshold, AAA reported Tuesday.

At $2.013 per gallon, the average is the lowest price for gas in the United States since 2009, and 79 cents per gallon lower than the 2015 peak. The price has fallen on 33 of the past 38 days, and the average national price is down two cents per gallon from last week's price.

Retail averages are below $2 per gallon in South Carolina, Missouri and Kansas, each at $1.79 per gallon. The highest average prices can be found in Hawaii, at $2.75 per gallon, and in California, at $2.65 per gallon.

The U.S. benchmark for oil, West Texas Intermediate, closed Friday at $35.62 per barrel, a drop of 60 percent since June 2014 and a price not seen since the recession period of 2008-2009. Global supply of oil is significantly outpacing demand, a situation expected to last into the new year and keep gas prices on the decline. The price of gasoline generally tends to fall during winter months.

An expected increase in Federal Reserve interest rates would likely result in a stronger U.S. dollar, which would make oil, priced in dollars, a less attractive investment for those holding other currencies. The result would worsen the global oversupply of oil and keep oil and gas prices low.