There is an interesting article about Petersburg, GA in "Beneath these Waters - Archeological and Historical Studies of 11,500 Years Along the Savannah River" by Sharyn Kane & Richard Keeton. Funded by the U. S. Army Corps of Engineers - Savannah District - Pub. 1993. Library of Congress Number: 94-142-455.

Also, if you Google Petersburg, GA and read the Wikipedia article you will find "...During the peak of its prosperity, from 1800 to 1810 it was the third largest city in Georgia after Savannah and Augusta....After 1810 the town slowly declined, finally reverting to agricultural land...."