As soon as a group starts having members, there's really no difference between an "astroturf" movement and a "grass roots" movement. Membership is determined by

As soon as a group starts having members, there's really no difference between an "astroturf" movement and a "grass roots" movement. Membership is determined by the same exact factors: member support for the movement, effectiveness of the movement in organizing and relative success in getting the message out. It's the difference between a tomato and a tomatoe. Most grass roots movements start with a some funds and a few interested people who get members to join and support their movement so they can afford the PR people and lobbyists they need...