Gas prices increased from $1.51 per gallon in 2000 to $3.27 in 2008. Gas prices dipped to $2.35 in 2009 and started to rise again in 2011, when the average price per gallon was $3.53.
Several factors affect gas prices, including demand, supply, taxes and distance from U.S. supply sources. In addition to federal gas taxes, states assess their own excise taxes on gas, and the western and mid-Atlantic states usually levy higher taxes than southern states. Localities that are far away from the ports and refineries where gas is imported and prepared also tend to pay more per gallon due to transportation costs.