Oct 26 (Reuters) - The U.S. Strategic Petroleum Reserve was created by Congress after the 1973-74 Arab oil embargo. The emergency oil supply is stored in underground salt caverns at four sites in Texas and Louisiana. * Current inventory - 694 million barrels. * Highest inventory - 700.7 million barrels in late August 2005. The Hurricane Katrina oil loans and sales reduced it during Fall 2005. * Current storage capacity - 727 million barrels. * Current days of import protection - 57 days. * Maximum days of import protection - 118 days in 1985. * Maximum drawdown capability - 4.4 million barrels a day. * Time for oil to enter U.S. market - 13 days from Presidential decision to tap the reserve. * Typical storage cavern - a diameter of 200 feet and height of 2,000 feet, enough to hold 10 million barrels.