Ferguson is 21,000 people (2/3 AA) in six square miles (roughly 2 miles in any direction). I would avoid the area armed or unarmed. Open carrying would be bearding the lion, that is "the man" in his den. Discretion is the better part of valor.
For comparison, the densest populated place in Wisconsin is Shorewood at ~8500 mile^-2 and I don't go there. My home is about 25 mile^-2.