White's City, NM, (just outside of Carlsbad Caverns NP) there is one station. Diesel is $4.49 and gas is $3.61.
Actually there is more diesel in a barrel of crude oil than of gasoline, but you can't just refine diesel more to get gasoline from it. You can get some conversion, but it makes for pretty expensive gas. Diesel used to cost less because there was more of it per barrel and the demand was not as high as for gasoline. Today, gasoline demand has fallen some due to cost but diesel is mostly used by commercial enterprise and heavy equipment and so the price has had very little effect on the demand, and it is actually higher than ever before. Just one of those supply and demand deals.
At least, that is what most economic magazines and columnists are saying. Those who prefer to believe in some big conspiracy are never going to believe that.