Where were the American carriers and why were they not in or around Pearl Harbor when the Japanese attacked?
The U.S. Pacific Fleet had three carriers at the time of the attack:
U.S.S Lexington was at sea with Task Force 12, ferrying aircraft to Midway Island.
U.S.S. Enterprise was at sea and returned to Pearl Harbor in the evening following the attack.
U.S.S Saratoga was in San Diego, following a refit, to embark her air group who were training onshore.