Rebuilding New Orleans.
Not only is there a fair amount of oil drilling and refining that happens in the area there is much shipment that goes on. I recall hearing substantial amounts (like half and greater) of our farm produce exports leave via New Orleans. The states along the Mississippi River would lose in such an erasure.
In fact, in the end we will all be surprised at how quickly New Orleans is rebuilt. I recall dire predictions in dealing with such catastrophes in the past and how quickly they were dealt with. Specifically the Kuwaiti oil fires. I remember hearing all sorts of gloom and doom about how they would be burning for years. Well, IIRC they were put out well within a year.
Right now it all seems insurmountable but there is a clever saying we all know: A trip of 10,000 miles begins with a single step.