BOSTON — For the past few presidential administrations, gasoline prices have tended to rise in the first 31 days after Inauguration Day, for various reasons. But 2017 may be different.

“This year could be the first time since [Bill] Clinton that gas prices drop following Inauguration Day,” Patrick DeHaan, senior petroleum analyst for Boston-based GasBuddy, told CSP Daily News.

After charting the national gasoline average for the first 31 days following the inauguration of a new president, DeHaan found that it tended to rise. This trend is documented at least back to 2000, when GasBuddy began collecting data. This rise includes 2000 and 2005 with President George W. Bush’s two terms, and 2009 and 2013 with the start of President Obama’s two terms.

This increase in the national average goes against seasonal norms. Typically, gasoline prices decline each year in January and February because of weaker demand and growing inventories. While he cannot account for the factors behind each post-inauguration increase, DeHaan suggested that an improving economy lifted oil demand—and ultimately gas prices—in 2009 and 2013.

But with the start of President Donald Trump’s term, prices are following the traditional seasonal track. Indeed, a downward trend started the week of Jan. 16, with the national average falling 3.2 cents per gallon (CPG) to $2.339 per gallon, the first weekly decline since November 2016, according to GasBuddy.

Prices fell in 36 states week over week, led by the Great Lakes states of Indiana (-13.9 CPG), Ohio (-13.1 CPG), Michigan (-10.9 CPG), Kentucky (-8.7 CPG) and Illinois (-6.2 CPG), as refinery problems resolved themselves. The Rocky Mountain states had the largest increases, led by Utah (5.8 CPG), Idaho (4.1 CPG) and Montana (3.4 CPG).

GasBuddy does expect prices to eventually begin to rise sometime after Valentine’s Day as refinery maintenance season and the transition into summer begins, “leading to gas prices that will mostly trend higher for two to three months,” said DeHaan.