Why aren't Charleston & Savannah the Boston & Philly of the south?

[Steely Dan]

i was just in charleston over the weekend for the 1st time. what a wonderful city! i've also visited savannah in the past, another wonderful small southern colonial city with charm and history pouring out of its ass.

they are probably the two best and most important colonial cities of the south (along with new orleans, which is a different beast). why didn't they grow into major seaport metropolises like the the old colonial port cities in the north did, such as boston and philly?

why are atlanta and charlotte such big deals? the urban bones of charleston and savannah are on another level. i mean, what if boston had a metro population today of 600,000 and albany was a metropolis of 6,000,000 people? or if philly was now home to 300,000 and state college was a burgeoning city of 3,000,000? wouldn't that seem really fucking weird? why was the script flipped in the south?