For comparison purposes, here are some quick numbers I gathered:

According to US Census Estimates (for 2008):

4,479,800 (South Carolina)
9,222,414 (North Carolina)
9,685,744 (Georgia)
24,326,974 (Texas)

One website I found showed the following (2006) population for the Atlanta area:

3,813,700 (what they called the 10-county Atlanta region)
4,917,717 (what they called the 28-county Atlanta Metropolitan Statistical Area - notice this is larger than the entire state of SC)

According to the same website, "in the past six years, the [Atlanta] metro area has added more than 142,000 people annually."
(that's more than the entire population of Columbia)