<human>:  Where did the Exxon Valdez spill its oil?
<bot>: The Exxon Valdez spilled its oil in Prince William Sound, Alaska. The oil spill occurred on March 24, 1989, when the tanker ran aground on Bligh Reef. The spill was the largest oil spill in U.S. history, and it was the largest oil spill in the world at the time.