As technology improves, particularly communication and transportation, human populations become more fluid and more distributed, able to flow in and out of geographic regions quickly, and to disperse more widely across larger areas. Over the past few decades we've seen a major population shift out of the densely urban East Coast into the deserts of the West, and why? Because many of the jobs required to support the business of the East can now be performed from anywhere in the world, and living conditions in the West (supported by technology) are higher than in the East. Land is cheaper, population is sparser... and the weather is more mild.
As we've seen recently with New Orleans, there's a periodic cost to living in a region with dangerous and unpredictable weather. For centuries New Orleans has been an essential waypoint into and out of North America, but with 21st century technology there's no need for half a million people to live there. Yes, we'll need dock workers, their supervisors, restaurants and supermarkets, utilities and car dealers, but most of the information services that our modern economy depends on can be moved elsewhere now with little transaction cost.