In December 1975, with memories of gas lines fresh on the minds of Americans as a result of the 1973 OPEC oil embargo, Congress established the Strategic Petroleum Reserve (SPR). The law was designed “to reduce the impact of severe energy supply interruptions” such as that caused by the embargo. Over time the U.S. government began to fill the reserve. At its high point in 2010, the level reach 726.6 million barrels. Since December 1984, the level has never been lower than 450 million barrels — until now.