The average price of a gallon of unleaded gasoline fell 7.5 cents to $2.139 for the week ending Jan. 12, continuing a slide that began in late June.
The average price is now $1.188 cents lower than it was at this time in 2014, according to data from the U.S. Department of Energy.
For the week, the average price fell in five regions tracked by the agency. The sharpest decline came in the Rocky Mountain region, where it fell 12.8 cents to $1.986. The cheapest gas can be purchased in the Gulf Coast for $1.911 per gallon on average.
The average price of gasoline now costs less than $2 per gallon in 18 states, according to the AAA's Daily Fuel Gauge Report. Gas is cheapest in Missouri, where it costs an average of $1.758 per gallon.
Meanwhile, the average price of diesel fell 8.4 cents to to $3.053. Diesel is now 8.33 cents lower than it was a year ago.