CALIFORNIA—The nationwide average gas prices fell below $2.20 a gallon for the first time about a month ago. According to the Oil Price Information, more than 48,000 stations have followed suit.

California’s fuel prices recently dropped to $2.65, but because of the state’s cap-and-trade rules, prices have increased. A portion of the revenue generated from the trade rule will be used for the construction of the state’s high-speed rail project.

If companies on the open market purchase more carbon credits, due to an annual decrease in the trade law, California gas prices will continue to rise in the coming years, even if gas prices remain static.

According to Gasbuddy.com, prices have only gone up by two cents since the carbon trade requirement went into effect on January 1.

Watchdogs are encouraging lawmakers to keep an eye on companies who would have to turn off their refineries to push prices up.