Average gasoline prices in Pennsylvania have hit $3 a gallon, the highest price since November 2014, according to AAA and GasBuddy.

Rising crude oil prices and the annual switchover to summer-grade gasoline — the lower-volatility fuel mandated for use in regions with persistent air pollution — have caused pump prices to surge recently, according to market-watchers.

"Government data highlighted a new record for gasoline demand was breached last week, and we're not even into the summer driving season yet," said Patrick DeHaan, head of petroleum analysis for GasBuddy. "The road ahead at the pump looks quite ominous if that demand number proves common in the coming weeks."

President Trump last week on Twitter singled out the Organization of Petroleum Exporting Countries for causing prices to rise. OPEC last year decided to curtail production when oil prices sank below $50 a barrel. The price is currently close to $70.

According to AAA, the average Pennsylvania gas price hit $3 Wednesday, up 6 cents in the last week. In New Jersey, the average was $2.84, up 9 cents in the last week. In Delaware, the average price was $2.74, up 10 cents in the last week.

The biggest cause for different prices in different states is motor fuel taxes: Pennsylvania has the highest gas tax in the nation, 58.7 cents, or 21.6 cents more a gallon than New Jersey.

Gasoline prices typically increase during the spring, when refineries schedule annual maintenance outages, reducing market supplies, and begin deliveries of lower-volatility fuels to regions operating under U.S. Environmental Protection Agency air-emission mandates.

Most coastal cities from Norfolk, Va., to Boston are required to sell reformulated gasoline during the summer. There are several other regional variations for fuel volatility — more volatile fuel evaporates more readily into the atmosphere — that depend upon the degree and persistence of local air quality.

"Instead of having one big pool of gasoline in the nation, you create a number of regional markets, that usually leads to some supply constraints," said DeHaan.

DeHaan anticipates that gas prices are likely to continue to drift higher before a possible peak in mid-May.