🚀 go-pugleaf

Actually, the Park Police have a reputation for UNDERestimating crowd size. They
make the estimate by taking an aerial photo of the crowd, then counting the
number of people in a small grid and multiplying that by the number of grids in
the photos.  However, they usually take the photo early in the day, often before
the "official" starting time of the march, so their estimates are frequently on
the small side (they take 'em early so as to get the count out to the press in
time for the 6 PM news shows).
 
During the anti-war days, they consistently underestimated crowd sizes (though
then the reasons were suspected to be political). I recall one gay march where
the official Park Police estimate was only 100,000, even though organizers of
the march had sold more than 200,000 buttons to the crowd (somehow I doubt that
every single marcher purchased two buttons <grin>).
 
I was surprised at the half million estimate for the pro-choice march, though. I
would have estimated it at about 350,000 myself, but it was very difficult to
get a good view of the entire crowd since they were widely scattered. I do know
that, at one point, there was a large crowd on the Mall, another large crowd at
the Ellipse, and a densely-packed stream of people from one end of the march to
the other.  How many people that represents is hard to say.