U.S. gas prices fall just below $4 per gallon nationwide for the first time since March, with the average slipping to slightly under the $4 mark overnight. Multiple outlets report the decrease follows President Donald Trump signing an agreement with Iran. The deal requires Iran to dilute its stockpile of highly enriched uranium and includes the waiver of U.S.-backed sanctions on Iran. Sources link the timing of the price decline to the announcement and possible impact on expectations for oil and fuel markets, though they do not cite specific drivers beyond the agreement itself. PBS also notes that despite the drop, U.S. gas prices remain substantially higher than a year earlier, reporting prices are about 25% higher than last year. Overall, the coverage focuses on the milestone of the average price crossing below $4 and the concurrent timing of the Iran agreement, while emphasizing that current prices are still elevated compared with the prior year.