from stratfor (registration required):

New Orleans: A Geopolitical Prize
By George Friedman
…
During the Cold War, a macabre topic of discussion among bored graduate students who studied such things was this: If the Soviets could destroy one
city with a large nuclear device, which would it be? The usual answers were
Washington or New York. For me, the answer was simple: New Orleans. If the
Mississippi River was shut to traffic, then the foundations of the economy
would be shattered. The industrial minerals needed in the factories wouldn’t
come in, and the agricultural wealth wouldn’t flow out. Alternative routes
really weren’t available. The Germans knew it too: A U-boat campaign
occurred near the mouth of the Mississippi during World War II. Both the
Germans and Stratfor have stood with Andy Jackson: New Orleans was the
prize.
Last Sunday, nature took out New Orleans almost as surely as a nuclear
strike. Hurricane Katrina’s geopolitical effect was not, in many ways,
distinguishable from a mushroom cloud. The key exit from North America was
closed. The petrochemical industry, which has become an added value to the
region since Jackson’s days, was at risk. The navigability of the
Mississippi south of New Orleans was a question mark. New Orleans as a city
and as a port complex had ceased to exist, and it was not clear that it
could recover.
The Ports of South Louisiana and New Orleans, which run north and south of
the city, are as important today as at any point during the history of the
republic. On its own merit, POSL is the largest port in the United States by
tonnage and the fifth-largest in the world. It exports more than 52 million
tons a year, of which more than half are agricultural products — corn,
soybeans and so on. A large proportion of U.S. agriculture flows out of the
port. Almost as much cargo, nearly 17 million tons, comes in through the
port — including not only crude oil, but chemicals and fertilizers, coal,
concrete and so on….
The oil fields, pipelines and ports required a skilled workforce in order to
operate. That workforce requires homes. They require stores to buy food and
other supplies. Hospitals and doctors. Schools for their children. In other
words, in order to operate the facilities critical to the United States, you
need a workforce to do it — and that workforce is gone. Unlike in other
disasters, that workforce cannot return to the region because they have no
place to live. New Orleans is gone, and the metropolitan area surrounding
New Orleans is either gone or so badly damaged that it will not be
inhabitable for a long time….
The displacement of population is the crisis that New Orleans faces. It is
also a national crisis, because the largest port in the United States cannot
function without a city around it. The physical and business processes of a
port cannot occur in a ghost town, and right now, that is what New Orleans
is. It is not about the facilities, and it is not about the oil. It is about
the loss of a city’s population and the paralysis of the largest port in the
United States….