Imagine the horror of Atlanta and Charlotte merging into a single massive sprawl of suburbs and freeways. That's essentially the nightmare scenario put forth in a recent study by North Carolina State University and the U.S. Geological Survey.

The study points out that urban expansion in the South's major cities over the next 50 years could create traffic-plagued, virtually unlivable megalopolises if growth continues as it has in the past. The prescribed prevention is a concerted effort to move towards denser, more centralized growth.

Specifically, the South needs to stop designing its cities around cars. That means regional planning to limit sprawl, including urban growth boundaries and better access to alternative modes of transportation.

The challenge for the Lowcountry will be in adjusting for increased density without losing the laid back charm that draws thousands of new residents and millions of tourists each year.

Improvements to the regional mass transit system are essential. The outlook should renew the initiative for light rail serving the region.

Charleston's "holy" skyline probably won't have to compete with skyscrapers in order to house the study's estimated 200,000 new residents expected by the middle of the century. The area's growth in this century is likely to be relatively modest compared to the explosions of sprawl predicted around and between Atlanta and Charlotte, which have dense, largely non-residential city centers and heavily populated suburbs. But the infamous traffic, endless webs of asphalt and epic daily commutes that plague those metropolises can serve as a cautionary tale.

If current growth trends continue, the Charleston metro area could approach 1 million residents in the next 50 years. Not a megalopolis by any measure, but certainly a planning challenge better addressed now than later.

Charleston can still avoid the sprawling mistakes of its larger southeastern city neighbors. Either that or invest in very comfortable cars in which to spend ever more hours in gridlock.