National Average: $1.89 (lowest price since February 2005)
National Low: $1.35 in Kansas City
Mark Perry estimates the annualized savings to be $317.4 billion, based on the drop in gas prices from the peak of $4.12 per gallon in July to the current $1.89 ($1.4235 billion annual savings for American consumers and businesses per penny decrease in gas prices, see calculations here).