After 2004 , the price increased until the average gas price reached a high of $ 4.11 per U.S. gallon in mid-2008 , but receded to approximately $ 2.60 per U.S. gallon by September 2009 .
After 2004 , the price increased until the average gas price reached a high of $ 4.11 per U.S. gallon in mid-2008 , then dropped approximately $ 2.60 per U.S. gallon as of September 2009 .