US Strategic Petroleum Reserve: Emptied, Refilled, and Emptied Again

The idea of a US strategic oil stockpile predates the crisis that finally created one. In 1944, wartime Interior Secretary Harold Ickes proposed an emergency crude stockpile on national-security grounds. In 1952, President Truman’s Minerals Policy Commission recommended the same thing. The 1956 Suez Crisis, which disrupted international oil transport, prompted President Eisenhower to consider it again. Each time, the warning was the same — global oil supply can be interrupted by geopolitics — and each time, no reserve was built.

It took the October 1973 Arab oil embargo, imposed after the Yom Kippur War by Arab oil producers against the United States and other supporters of Israel, to change that. Gasoline lines, price controls and fuel rationing gave Americans a direct, visible experience of energy vulnerability that three prior proposals had not. In 1974, major oil-importing nations formed the International Energy Agency (IEA) and agreed to maintain emergency stocks equal to at least 90 days of net imports — a framework the future SPR would help the US meet. On 22 December 1975, President Gerald Ford signed the Energy Policy and Conservation Act, creating the Strategic Petroleum Reserve, with an original policy ceiling contemplating up to one billion barrels.

Storing hundreds of millions of barrels above ground would require enormous, expensive, hard-to-protect tank farms. Engineers instead turned to naturally occurring salt domes along the Texas and Louisiana Gulf Coast. Water is pumped down a well to dissolve a cavity out of the salt — a process called solution mining — and the resulting brine is pumped out, leaving a vast underground cavern that crude oil then fills. Salt’s very low permeability helps it seal small fractures, and a single cavern can hold millions of barrels at a fraction of the cost of surface tanks.

The first crude — about 412,000 barrels of Saudi Arabian light — arrived on 21 July 1977. The 1979 Iranian Revolution triggered a second oil shock within the decade, reinforcing the case for the reserve and accelerating purchases through the early 1980s. Filling continued through the 1990s and 2000s, including a directive from President George W. Bush after the September 11, 2001 attacks to fill the reserve toward capacity. By 2009, the SPR reached its historical year-end peak of 726.6 million barrels — at 42 US gallons per barrel, more than 30 billion gallons of crude held underground. Even a reserve that size is finite: its purpose was always to buy time during a disruption, not to replace the oil market indefinitely.

The SPR was not used in a major emergency for its first fifteen years. That changed with Iraq’s 1990 invasion of Kuwait: the 1990–91 Gulf War produced the reserve’s first major emergency sale, as part of an internationally coordinated response. In 2005, Hurricane Katrina devastated Gulf Coast refining and pipeline infrastructure, and the SPR responded — not to a foreign embargo, but to domestic infrastructure failure, expanding what “energy security” was understood to cover. In 2011, civil conflict in Libya removed oil from world markets and the US drew down the SPR again as part of a coordinated IEA release.

Through the 2010s, the American shale revolution sharply increased domestic oil production and cut import dependence, prompting a genuine policy debate: if the US imports far less oil, does it still need a 700-million-barrel reserve? Congress’s answer, starting in fiscal year 2017, was a series of mandated non-emergency sales tied to budget and modernisation priorities — meaning SPR inventory was already declining years before 2022, for reasons that had nothing to do with any single geopolitical event. A different kind of stress hit in 2020: COVID-19 collapsed oil demand so severely that US crude futures briefly traded below zero, and DOE used SPR capacity in reverse, letting commercial producers store oil there temporarily through exchange arrangements.

Russia’s February 2022 invasion of Ukraine sent a shock through global energy markets: Russia is one of the world’s largest oil exporters, and sanctions, buyer avoidance and shipping disruption pushed prices sharply higher, feeding directly into US gasoline prices. After an initial coordinated IEA release in March, President Biden announced a far larger step on 31 March 2022: a target of 1 million barrels per day for six months, totaling 180 million barrels — the largest emergency release in the reserve’s history. Supporters argued the shock was extraordinary and justified using the reserve for its intended purpose; critics argued it cut America’s emergency cushion too far and questioned whether it was also aimed at influencing prices rather than responding narrowly to a physical shortage. That debate continues, but one number matters most for what came next: the emergency barrels sold in 2022 fetched an average price of about $95 per barrel. Year-end SPR inventory fell to 372.0 million barrels, down from 593.7 million a year earlier.

Once the 2022 emergency passed, DOE began refilling the reserve through three separate mechanisms: direct purchases when crude traded at attractive prices (DOE initially targeted $79/barrel or below), exchange returns from companies that had previously borrowed SPR oil, and cancelling future mandated sales that Congress had scheduled years earlier — effectively raising future inventory by simply not selling, rather than buying anything back. By the time the Biden administration made its final purchase, DOE reported it had directly purchased about 59 million barrels at an average price under $76, and separately secured roughly 140 million more barrels by working with Congress to cancel mandated sales through fiscal 2026 — together described by DOE as securing about 200 million barrels for the reserve. Year-end inventory rose from 354.7 million barrels in 2023 to about 394 million in 2024 and 411 million barrels by the end of 2025.

On 28 February 2026, Israel and the United States began strikes against Iran targeting its nuclear and ballistic missile programmes. In response, Iranian forces declared the Strait of Hormuz — the channel through which roughly a fifth of the world’s petroleum and LNG normally passes — closed starting 4 March 2026, threatening and attacking vessels attempting to transit it. Oil prices spiked sharply: US crude posted its largest weekly gain since futures trading began in 1983, with benchmark prices climbing into the $90-a-barrel range.

On 11 March 2026, the International Energy Agency and its 32 member nations unanimously agreed to a coordinated release of 400 million barrels of oil and refined products. President Trump authorised the Department of Energy to release 172 million barrels from the SPR as the US contribution, with delivery planned over roughly 120 days. Crucially, DOE structured much of this release as an emergency exchange: companies receive SPR crude now under contracts requiring the original volume, plus additional barrels, to be returned later. Through May and June 2026, DOE awarded multiple exchange contracts covering tens of millions of barrels as the drawdown continued.

By 10 August 2026, the SPR had fallen below 300 million barrels for the first time since 1983. The decline continued: EIA reported 285.4 million barrels for the week ending 4 September 2026 — the lowest level since November 1982 — down from about 405.2 million barrels a year earlier, a drop of nearly 30% in twelve months. Reporting through mid-September put the level essentially unchanged at around 285 million barrels. Energy Secretary Chris Wright has said the administration intends to proceed with the drawdown as planned, while industry and oversight reporting has flagged growing strain on infrastructure that has now absorbed two record-scale drawdowns — 2022 and 2026 — within four years.

Before the 2026 drawdown, the Government Accountability Office reported a DOE estimate that restoring the SPR to a roughly 680-million-barrel effective peak capacity would require about 250 million additional barrels, costing around $20 billion at $80-a-barrel crude — on top of a separately identified $1.4 billion Life Extension Phase 2 modernisation programme and more than $100 million in immediate cavern and pipeline repairs. That estimate was built around an SPR sitting near 400–430 million barrels. At today’s ~285-million-barrel level, the arithmetic gap to the same 680-million-barrel target is closer to 395 million barrels — meaningfully larger than the figure GAO’s estimate assumed.

Even with money in hand, a fast refill runs into physical limits: injection rates, pipeline capacity, cavern maintenance, and the risk that large government purchases themselves move the oil market. And every barrel released in 2026 as an exchange rather than a sale carries a contractual promise of return — meaning some of this gap should eventually close on its own as exchange partners deliver their obligations, on a timeline that is not yet fully public.

Because of this chain, releasing more SPR crude does not by itself fix a refinery-capacity or distribution bottleneck — it only adds crude supply at the front of a system that still has to process and move it.