gasbuddy.com
gaspricewatch.com
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Gas buddy has links to every state, then you can go to the different locales in each state. Its listings depend on the members posting prices. If you sign up as a member, you can also keep a log of your fuel. I've been on it for several years, and it's an excellent tool for tracking your fuel expenses and mileage. Each time you fill up, just put in the name of the station (Exxon, Phillips 66, etc.), then the price, total gallons, and vehicles miles, and it figures the rest.
If you can PM your e-mail address, I'll "recommend you" which will also give me additional points on the site.
Hope you have a save trip.