The national average price for a gallon of regular unleaded gasoline reached $3.977 on Tuesday, according to AAA. [1] The number is not four dollars. It is close enough that the difference — 2.3 cents — is smaller than the variation between one side of most American towns and the other. For practical purposes, the United States is now a four-dollar-gas country.

The speed of the increase is more striking than the level. Three weeks ago, before the war with Iran began, the national average was $2.98. The rise of roughly one dollar per gallon in 21 days represents one of the sharpest sustained increases in AAA's records, exceeded only by the initial weeks of the 2022 spike following Russia's invasion of Ukraine. [1][2]

The cause is singular and straightforward. The war with Iran has disrupted shipping through the Strait of Hormuz, the chokepoint through which roughly 20 percent of the world's oil supply normally passes. Traffic has dropped to a fraction of normal volume. Iran's selective passage policy — announced Tuesday — formalizes a restriction that has been in effect operationally since early March. Brent crude is trading above $105 per barrel, up from $72 before the conflict began. [2]

The cost falls unevenly. AAA data show California averaging $5.14 per gallon, with some stations in Los Angeles County above $5.50. The Gulf Coast states, traditionally the cheapest market, have crossed $3.60. Only a handful of states — Mississippi, Louisiana, Texas — remain below $3.70, and all are rising daily. [1]

USA Today reported Tuesday that the average American household will spend approximately $500 more on gasoline this month than in February if current prices hold. For families earning below the median household income, that increase consumes a larger share of disposable income than any single-month price shock since 2008. [2]

The political dimension is inescapable. President Trump built his 2024 campaign partly on the promise of lower energy costs. The administration has blamed Iran for the price increase — accurately, in the sense that the war is the proximate cause — while critics note that the decision to launch strikes on Iranian nuclear facilities was itself a policy choice that carried foreseeable energy market consequences.

The Federal Reserve, which had been expected to cut rates this spring, is now facing a stagflationary scenario: rising energy costs that simultaneously slow growth and push inflation higher. Futures markets are pricing in a more than 50 percent probability that the next rate move will be a hike, not a cut. [2]

Four-dollar gas is a number that changes behavior. It changes commuting patterns, vacation plans, and votes. The last time it happened — the summer of 2022 — President Biden's approval rating hit its lowest point. Whether the current war can sustain public support at these prices is the question that no poll can yet answer.

-- LUCIA VEGA, São Paulo