A piece of extraordinary news traveled a long distance in a very short time, mobilizing an entire region to arms. Think, for a moment, about the last expensive restaurant you went to, the last expensive piece of clothing you bought, and the last movie you saw. But for all that, word of mouth remains very mysterious.
People pass on all kinds of information to each other all the time.
There is a small restaurant in my neighborhood that I love and that I've been telling my friends about for six months. But it's still half-empty. In the case of Paul Revere's ride, the answer to this seems easy. But if you look closely at the events of that evening, that explanation doesn't solve the riddle either. He was carrying the identical message, through just as many towns over just as many miles as Paul Revere.