Gas prices in metro Detroit jumped past $4 a gallon this week, and the federal numbers released Friday explain why: the U.S.-Israeli war in Iran has sent energy costs through the roof, and Michigan drivers are feeling it at every fill-up.

The Bureau of Labor Statistics reported that overall consumer prices rose 0.9% in March compared to February. That’s three times the 0.3% increase from the month before. Year over year, prices across all categories climbed 3.3%, the steepest annual jump since May 2024.

Gasoline drove most of that spike. Gas prices rose 21.2% in March alone. Fuel oil and gasoline combined were up 10.9% month over month, and airfare costs climbed 2.7% as jet fuel prices followed crude oil upward.

What’s behind the surge

The short answer: the Strait of Hormuz.

President Donald Trump launched a joint military campaign with Israel against Iran on Feb. 28. Iran responded by effectively closing the Strait of Hormuz, the narrow waterway connecting the Persian Gulf to the open ocean. One-fifth of the world’s petroleum moves through that chokepoint. According to the International Energy Agency, Iran’s de facto takeover of the strait has caused the largest supply disruption in the history of the global oil market. Not a small claim.

Before the war started, a gallon of regular gas hadn’t cracked $3 all year. As of Friday, the national average sits at $4.15 per gallon for regular, according to AAA. Diesel is averaging $5.68 nationwide.

Those numbers hit harder in a city built around the car. Detroit’s public transit isn’t going to absorb the shock. If you’re commuting from Warren or Westland or out to Dearborn for work, there’s no real alternative to driving. That extra dollar-plus per gallon adds up fast, somewhere between $15 and $30 more per tank depending on your vehicle.

The strait, the ceasefire, and the math

A ceasefire was agreed to Tuesday evening. It hasn’t changed much on the water.

Prior to the war, roughly 140 vessels moved through the Strait of Hormuz every day. On Tuesday, ten tankers transited the waterway. On Wednesday, one. The Joint Maritime Information Center, which tracks vessels transmitting location data worldwide, confirmed those figures. Iran is still controlling the strait despite the ceasefire, which means supply disruption continues, which means prices stay elevated.

There’s no near-term scenario where this just snaps back to normal. Global oil markets don’t recover from the largest supply disruption in their history because two governments signed a piece of paper.

The political fight

Democrats spent Friday making sure nobody forgot who started the war.

Democratic National Committee Chair Ken Martin said Trump is “pushing working families to the brink.” He pointed to Trump’s campaign promise to lower prices on day one. “Instead he waged an unhinged trade war and started an unpopular war with Iran,” Martin said, “and what have Americans gotten in return? Nothing except even higher prices.”

Affordability is shaping up as the central issue heading into the November midterms, which will determine control of Congress. Republicans are defending majorities in both chambers, and $4-plus gas in the suburbs of every major American city is a difficult thing to explain away.

For Detroit specifically, this lands on top of an already strained household budget picture. The region hasn’t fully recovered from the inflationary pressure of the early 2020s, and wages in many service and trades jobs have not kept pace. Higher fuel costs ripple out beyond the pump, touching food delivery, construction supply chains, heating costs, and the price of anything that moves on a truck.

Michigan Advance first reported the CPI figures alongside conditions at the pump across the state, including a Shell station in Howell clocking in at prices that reflect the new national reality.

What to watch

The strait situation is the only variable that matters right now. If Iran actually reopens the waterway to normal tanker traffic, crude prices will ease and pump prices will follow, though with a delay. If the ceasefire holds only on paper while Iran keeps blocking ships, $4 gas could look cheap by summer.

The next CPI report drops in May. Watch the energy subcategory. That’s where this story will either get worse or start to turn.