Huge hat tip to Left Coast Rebel, as he's the first I saw with this posted. Well done, sir.
Here's a well explained breakdown of the numbers in attendance at a number of Washington, D. C. events, including the 9/12 Protest of 2009.
Zac Moilanen at Indiana University has concluded an approximate 1,782,760 attendees.
And we've only just begun.
The Real Number of Protesters - Zac Moilanen