Located along the Gulf of Mexico, the SPR is the world's largest supply of emergency crude oil. Established after the 1973-74 oil embargo, the federally owned oil stocks are stored in 63 underground salt caverns in four locations in Louisiana and Texas. SPR has the capacity to store more than 700 million barrels of sour and sweet crude oil and maintains a minimum of 500 million barrels in reserves. This is estimated to be a 90-day supply for the entire U.S. in the event of a disruption in the supply chain.
Decisions to withdraw crude oil from the SPR are made by the Secretary of Energy or the President of the United States, depending on the size of the withdrawal. The SPR has been used under these circumstances only three times, most recently in June 2011 when the president directed a sale of 30 million barrels of crude oil to offset disruptions in supply due to Middle East unrest. In April 2014, the United States government also released five million barrels of sour crude from the emergency stockpile in a test to verify how new pipelines and other infrastructure might affect the government's ability to transport the crude out of the underground caverns.
The SPR management office is located in New Orleans, Louisiana. Each of the SPR's four storage sites is located near a major center of petrochemical refining and processing and contains multiple underground caverns.
- Bryan Mound, near Freeport, Texas, is the largest SPR site with cavern # 5 owning the distinction of being the world's largest man-made oil storage container.
- Big Hill, near Winnie, Texas, is the newest SPR storage site with an optimized layout.
- West Hackberry, near Lake Charles, Louisiana, has caverns that are presently being degassed to verify market oil can be delivered to meet immediate energy demands.
- Bayou Choctaw, near Baton Rouge, Louisiana, is the smallest SPR site. The facility has often been called upon and has demonstrated success in achieving mission critical crude oil exchanges as a result of oil supply disruptions created by hurricane conditions on oil production in the Gulf of Mexico.