For the first time since April 2, average gas prices in Erie County are below $4 a gallon.

On June 21, the average price of regular gas across Erie County dipped to $3.99, according to gasprices.aaa.com.

Erie County has the 14th cheapest gas in Pennsylvania. The top three cheapest gas prices in the state are in Williamsport at $3.64, followed by Bloomsburg and Berwick which are both at $3.78.

The last time the average price was under $4 per gallon in Erie was on April 2 when they were at $3.96. Average prices jumped to $4.12 per gallon on April 3 and averaged $4.64 in May.

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Diesel prices drop across Pennsylvania

When the price of regular gas was over $4 a gallon, the price of diesel reached over $6 a gallon. As of June 22, the average price of diesel in Pennsylvania is $5.49 a gallon.

Diesel fuel prices are trending downward in Erie County. AAA data shows the price on June 21 was $5.51 and $5.60 on the week of June 14-20. Diesel prices averaged $5.92 in May.

Why are gas prices dropping across the nation?

Across the country, gas prices started to decrease around June 18, the morning after U.S. and Iranian officials signed a memorandum of understanding which was aimed at ending the war.

AAA reports that crude oil prices have been dropping amid peace talks with Iran. As of June 14, the oil prices were trading below $80 a barrel.

Nerdwallet.com reports that “since the United States and Iran have signed a ‘memorandum of understanding,’ that extends to a sometimes-shaky ceasefire and promises to reopen the Strait of Hormuz to tanker traffic.”

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Where to find the cheapest gas in Erie County?

Now that gas is under $4 in Erie, GasBuddy lists the cheapest gas across Erie County on June 22 at:

Holiday at 605 Parade St. and Speed Check at 1001 East Avenue at $3.79 per gallon;

Gulf at 2747 W. 12th St. and Kwik Fill at 7725 Perry Highway at $3.89 per gallon;

Sheetz at 750 Peninsula Drive at $3.93 per gallon.

Contact Nicholas Sorensen at Nsorensen@usatodayco.com.

This article originally appeared on Erie Times-News: Where to find the cheapest gas in Erie County