

Walmart heiress Christy Walton bought ONE full-page color ad in the New York Times. The rallies themselves appear to be independently organized — you can volunteer to host one on their site — and you can get a good idea of who’s actively involved in organizing them by looking at their partners page.
Pleased to see that this is actually free, in the open source sense (it’s GPL3). It took me an ungodly number of clicks to get to the project’s github repo, so I’ve saved you that trouble.