On March 24, 1989, the tanker Exxon Valdez ran aground on Bligh Reef in Prince William Sound, Alaska. Within six hours of the grounding, the Exxon Valdez spilled approximately 10.9 million gallons (259,500 barrels) of its 53 million gallon cargo of Prudhoe Bay crude oil. The oil would eventually impact more than 1,100 miles of non-continuous coastline in Alaska, making the Exxon Valdez the largest oil spill in U.S. waters at the time.