Location: Though price changes are usually tracked using national averages, the price you pay varies widely from one pump to the next. Taxes, transportation costs, local supplies, changes in commuting patterns can all act independently on gas prices, which can amplify the impact of crude price runups and crashes.
That's why "it may not be surprising that we found more asymmetry at the local level than at the national level," according to economists at the St. Louis Federal Reserve.
The weather: Price changes also vary widely with the season. In much of the country, refiners have to produce different blends for summer and winter months. Summer fuel is more expensive. "During the winter, the rate at which gas prices are pulled down by oil prices appeared to be higher than it was during the summer," according to St Louis Fed researchers.
Taxes: When you top off your tank, you're paying for more than just the cost of the gasoline. In states where taxes are high, that can be a big part of filling up. When gas prices rise, you pay extra for the gas, When they fall, you still pay the full tax, which are levied per gallon rather than per dollar. So taxes skew the ratio between the price of gasoline and crude oil, researchers at the Cleveland Federal Reserve have noted.
Global demand: Until relatively recently, gasoline refined in the U.S. was sold only in the U.S. Though still a small share of production, the volume of U.S. exports is rising as U.S. demand has shrunk. That's helped cushion the downward price pressure from falling crude prices.
(CORRECTION: This story has been updated to correct the percentage drop in gasoline prices.)