(CNN) -- Here's a look at what you need to know about the U.S. Strategic Petroleum Reserve.
Facts: The U.S. Strategic Petroleum Reserve is a stockpile of crude owned by the U.S. government.
It provides a back-up supply of crude oil if the commercial oil supply is disrupted.
The crude oil is stored in underground salt caverns in a government complex along the Texas and Louisiana Gulf Coast. Salt formations are the cheapest, most environmentally safe way to store crude oil.
The current storage capacity is 727 million barrels. Here is the current inventory.
The average price paid for the oil in the Reserve is $29.90 a barrel.
In 1985, the SPR had 490 million barrels of oil in reserve. That amount could have replaced the the supply of imported oil for 118 days.
In 2013, the SPR, at the current level of 696 million barrels, the SPR could replace the supply of imported oil for 93 days.
From the time the President makes the decision to tap into the SPR, it takes 13 days for oil from the SPR to reach the U.S. market.
The SPR could be used for three possible types of drawdowns: a full drawdown to remedy a "severe" shortage; a limited drawdown to prevent a significant shortage; or a test sale or exchange of up to five million barrels.
Timeline: December 22, 1975 - President Gerald Ford establishes the SPR when he signs into law the "Energy Policy and Conservation Act." The law is created in response to the oil embargo of 1973-1974 and the severe effect it had on the U.S. economy. It mandates that the U.S. maintain a stockpile of one million barrels of petroleum, which is the largest emergency supply in the world.
July 21, 1977 - The first oil, from Saudi Arabia, is delivered to the SPR.
January 16, 1991 - President George H.W. Bush orders the first emergency drawdown of the SPR.
September 2000 - President Bill Clinton releases 30 million barrels of oil in the SPR, to increase home heating oil supplies and lower gasoline prices which had risen to more than $2 a gallon in some areas.
November 13, 2001 - President George W. Bush orders the SPR to be filled to its maximum capacity of 700 million barrels.
September 1, 2005 - U.S. Energy Secretary Samuel Bodman announces that six million barrels of crude oil will be released/loaned to ExxonMobil Corp. from the Strategic Petroleum Reserve. The Department of Energy also confirms that Valero Energy Corp. will receive 1.5 million barrels of crude from the SPR for use at its refineries. This is in response to devastation of Hurricane Katrina.
April 25, 2006 - President George W. Bush announces that he has decided to temporarily halt deposits to the nation's strategic petroleum reserve, freeing more oil for consumer needs and seeking to relieve prices at the pump.
May 19, 2008 - President George W. Bush signs a bill halting deliveries to the petroleum reserve for six months. It is hoped that the measure will bring down the record high price of gasoline in the U.S.
September 12, 2008 - President George W. Bush announces that oil from the reserve will be released to help Louisiana recover from Hurricane Gustav.
June 23, 2011 - The U.S. Department of Energy announces that it will release 30 million barrels of oil from the Strategic Petroleum Reserve to alleviate Libyan supply disruptions.
August 2012- The U.S. Department of Energy announces that it will loan one million barrels of oil to Marathon Petroleum to address the short term impact Hurricane Isaac had on the company's refining capacity.