JC Leahy, Accountant on the Scene, Washington, DC
Based on on-the-scene evaluatioin lasting until 1:30 pm on 9/12, the Journal of American Ideas Today originally estimated a 9/12 March on Washington total attendance of a million to 1.2 million. This compared with other estimates ranging as high as 2 million. However, our best current information is that Pennsylvania Avenue is 180 feet wide including sidewalks. We know from having walked the entire walk that folks were not marching on the sidewalks. Allowing for 40 feet of sidewalks, the march's pathway would be 140 feet wide. If Pennsylvania Avenue is only 140 feet wide, then 70 marchers passing over an imaginary intersecting line at any given moment might be too high a figure because that would be one person every 2 feet. We therefore reduce the figure of 70 to 50 marchers passing at any given moment at a speed of approximately 2 miles per hour. It would take only a second for each set of 50 to pass over the imaginary line, making the rate of passage 3,000 per minute. This rate happens to agree with the rate estimated by a videographer whom JC Leahy interviewed at the scene. We know from actual observation that the march ended at 1pm but that the density of marchers was much less by that time. Our best on-the-scene information is that the march went at "full volume" for 2.5 to 3 hours and tapered off after that. If we say, 2.5 hours at full volume at 1.5 hours tapering off to zero at a linear rate, at a "full" rate of 3,000 per minute or 180,000 per hour, that give us: 180,000 x 2.5 plus 90,000 x 1.5 = 585,000 marchers arriving via Pennsylvania Avenue. Some marchers arrived by other routes. If we allow 10%, or 58,500, from other routes, this gives us 643,500 attendees. Round it to 640,000 -- that is the Journal of American Ideas Today's revised attendance estimate for the 9/12 March on Washington. I would add that there is a zero percent chance that fewer than 100,000 attended, as reported my many in newspapers and broadcast.