Social Circle GA is first listed in the USPOD 'Official Postal Guides' in 1874 and is still in operation today.
Anyone who is interested in postal history can download the entire run of them from the Stamp Smarter website. http://stampsmarter.com/learning/Home_USPOD.html
They are fully searchable. To make for blazingly fast searches across all of the downloaded PDFs, you can easily build a PDF index (.pdx file extension) in Acrobat. Once saved on your computer, it takes only about 30 seconds to search the entire run for key word(s).