Inspired by low gas prices, more than 91 million Americans opt to drive 50 or more miles during the holiday season.

U.S. average gas prices fell below the $2-per-gallon mark on Monday, Dec. 21, just in time for holiday travel.

Today’s national average is $1.998 per gallon. Gas hasn’t been this inexpensive since March 25, 2009, according to a report by AAA.

AAA reported that falling pump prices have saved Americans more than $115 billion on gasoline—more than $550 per licensed driver—so far this year. More than 91 million Americans are expected to take advantage of the lower gas prices by driving 50 or more miles during the holiday season.

Travelers may even find gas for a lot less than the national average. More than two-thirds of U.S. stations already are selling gas under $2 per gallon. Roughly 1% of stations are selling gas for an average of $1.59 per gallon, and more than 13,000 stations are selling gas for under $1.75 per gallon. The most common price nationwide is $1.899 per gallon, AAA reported.

The state with the lowest average cost of gas is Missouri ($1.77). Hawaii has the highest at $2.73 per gallon, followed by California at $2.72 per gallon.