"As of January 1, 2015 single-hull oil tankers are no longer allowed in U.S. waters.

The Oil Pollution Act of 1990, passed after the disastrous 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, required that all new tankers and tank-barges be built with double hulls to prevent similar oil spills.

For the first 25 years after the law was passed, single-hull tankers were still allowed to operate, but now those tankers are at the end of their operational lives and can no longer carry oil as cargo in U.S. waters."

Environment News Service had the story January 2, 2015. [2]