They make it a point not to engage in crowd estimation for just this reason. Once teh overhead helicopter pictures are made available we'll all know what the "true" number is, in spite of what these folks say.
Doesn't matter whether they had 100,000 or a million, the only way we would get out of Iraq now is for congress to shut down funding of the war and that's not gonna happen. They can protest, throw tantrums or whatever they choose but they are wasting their time.
My husband and I had always heard that pro-life rallies were notoriously undercounted. So he, the Ph.D in math, counted a march in Boston, as it went by - no more than six abreast on the sidewalk, with a couple hundred left on the Common. He got 4000.
Police said 15,000. Organizers said 20,000. We really would have liked it to be that many, but it wasn't. I tend to doubt any really large estimate, unless you have a mathematician counting people as they file past, or looking at an aerial photograph.