If a nuclear deal is reached with Iran this week, oil prices could further dip, with pump prices to potentially follow.

On Monday, March 30, the national average price for regular unleaded gasoline rang in at $2.42 per gallon—only two cents more than one month ago but $1.13 less than the same date last year. The national average has now fallen for 17 of the past 23 days, according to a report by AAA.

While several weeks ago refineries went offline and drove gas prices higher in the Midwest and West Coast, this week as those refineries resume production, it’s helping prices to dip in those same regions. Lower oil prices have also helped lower gas prices in every state. California continues to post the highest pump prices in the nation at $3.20, while South Carolina continues to be the lowest at $2.10, followed by Tennessee at $2.14 and New Jersey at $2.16.

After increasing above $50 per barrel last week, the price of West Texas Intermediate crude oil has dropped. “Crude prices have fallen to multi-year lows due largely to ample global production. The possibility of increased exports from Iran should a nuclear deal be reached this week would further increase production and has for now offset any ‘risk premium’ stemming from regional stability due to violence in Yemen. A possible deal between the West and Iran could bring an estimated 500,000 barrels per day of additional oil to the global market, which would add more supply to an already well-supplied market and exert further downward pressure on crude prices,” AAA reported.