A new map of the U.S. on GasBuddy.com illustrates the disparity of gasoline prices across the U.S. Red, representing the most expensive gas, colors California and the West Coast, and parts of New England. Deep green, representing the cheapest gas, appears only in three states; Alabama, Missouri and South Carolina.

Why these three states? Two factors make the difference; proximity and taxes. Louisiana is the site of many of the nation's refineries (as we learned painfully in the aftermath of Katrina), so the cost of transporting fuel to the stations in nearby Alabama is much less. Ditto Missouri- while the state does not have refineries, many of the underground gas lines that distribute fuel around the country run through the state.

Missouri also takes a relatively light tax cut off of gasoline sales- 36 cents, vs. 66.6 cents in Illinois, 40.4 cents in Iowa, and 43.4 cents in Kansas. This accounts for South Carolina's inclusion in the lowest price gas class. It's tax burden per gallon is only 35.2 cents, lower than all the lower 48 states except New Jersey. In NJ, the prohibition against self-serve pumps eats up much of the tax savings, however. The state you would expect to have the cheapest gas, Louisiana, taxes at a slightly higher rate of 38.4 cents.

If you want really lightly taxed gas, though, try Alaska, at 26.4 cents. Just because the state has oil wells, though, don't expect cheap gas. It has to be shipped off to be refined, then shipped back, resulting in prices well above $4.00 a gallon.

The highest tax loads on gas, by the way, are found in California (74.9 cents), Illinois, and Michigan (60.7 cents).

If you want cheaper gas, follow the Mississippi River. Six of the 11 cheapest states for gas rest on its shores. If you have to visit California, take a bike.