Americans drove fewer miles in December for the 14th month in a row, but the decline was not as steep as in previous months thanks to cheaper gasoline prices that encouraged additional travel in some states, the U.S. Transportation Department said on Thursday.

U.S. highway travel was down 1.6 percent in December compared to a year ago, falling 3.8 billion miles to 237 billion miles.

That was a much smaller drop than the 5.4 percent decline seen in November or October’s 3.7 percent falloff in  reduced total highway travel, falling pump prices during December helped keep some drivers on the roads longer, the department said. The average price for regular unleaded gasoline declined 20 cents a gallon over the month.

Nonetheless, December was still the 14th straight month of declining highway travel, which now tops 115 billion fewer miles driven since November 2007.