Walmart is decreasing its gas prices by 10 cents per gallon until Sept 30.

Superstore mogul Walmart is offering 10 cents off the price of a gallon of gas this Fourth of July weekend at Murphy USA and Walmart stores. The deal, which is available in 18 states, started Wednesday and is good until September 30, 2011.

To get the discount, shoppers must have a Walmart gift card or credit card. “Perhaps most amazing,” adds USA Today, “Walmart says that there are no restrictions, including no requirement for store purchases in order to get gas discounts at Walmart stations.”

The deal, however, isn’t available in states like California and New York, where gas prices average $3.80 and $3.85 today. But, drivers in states throughout the Midwest and Southeast can get the deal. Arkansas, Georgia, Idaho, Illinois, Indiana, Iowa, Kentucky, Louisiana, Michigan, Mississippi, Missouri, New Mexico, North Carolina, Ohio, South Carolina, Tennessee, Texas and Virginia are included.

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