So, what's a SoBo? If a NoBo is someone that hikes the trail from Georgia to Maine heading North, then a SoBo is someone  who hikes the trail starting up on Mt. Katahdin, Maine, and ends at Springer Mountain, Georgia. Though North to South seems like a pretty logical way to hike, in reality, it is the least popular way to hike the trail in today's world. Hiking SoBo is arguably the more diifficult and least attractive way to hike compared to hiking NoBo. The Appalachian Trail Conservancy actually warns on their website that only experienced hikers should attempt to start at Mt. Katahdin. 

Some of the reasons a majority of hikers choose not to hike South bound are: 

To begin with, hikers aren't allowed to begin their South bound hike until the necessary trail opens  around mid-May.This is why the ATC website reccommends that you start your hike after June or mid-July. Another reason, is that the hike starting at the famous Mt. Katahdin mountian top is anti-climactic, and there are several hikers that would rather end on a note similar to the peak of Mt. Katahdin then the relaxed pathway of Springer Mountain in Georgia. When you start hiking from Maine to Georgia, that means that you are having to work through the toughest parts of the trail in the very beginning, when your muscles have not become conditioned to the daily intense exercise such as hiking. Also, one other reason why people usually do not like  to hike SoBo, is due to the lack of people who hike going south. If you are like to hike SoBo, you may be stereotyped and thought of as anti-social.

Because of the reasons as to why South Bound hiking is not the most popular choice, SoBo's are sometimes stereotyped as inexperienced, anti-social, and strange.

This marker was used all along the Appalachian Trail in its earlier stages of life. On the bottom half of the marker, you can see the phrase "Maine to Georgia," which means South bound. 

Though, hiking SoBo is not the most sought after direction in the modern world of AT hiking, it actually made sense and was advertised with the Appalachian Trail markers and Appalachian Trailway News cover in the beginnings of the Trail. When you look at the original Appalachian Trail marker, the bottom half says "Maine to Georgia," which is South Bound. This same marking is on several every cover of the Appalachian Trailway News publication, up until the 1973 publications. You can see them typicall in the top left hand corner of the cover page.