Good question, Tennyson.  I couldn't locate a central office, only a website, but they appear to have locations everywhere in the U. S. and elsewhere.

All of the above is exactly the point I was trying to raise. BLM is indeed a movement, but it has no real organized head or voice. It consists of anyone who locally wants to protest. That is OK, but like many protests, without a head it winds up being whatever the current protesters want it to be. 

That said, most of the major campaigns today have had to deal with it in one form or another. There is a HUGE divide in how the different candidates have dealt with it. To Mr Clinton's actions, he at least tried to talk to them as opposed to telling people to "get them out" or endorsing hateful reaction.