Crowd Size in San Francisco January 18

It would bring me great joy to believe that 1/3 of a million people got their butts out to protest the pending war. However, as a participant I cannot believe the estimate provided in this section. The problem is not with the author's multiplication, but rests with some of the assumptions made. Start with the distance from the ferry terminal to the Civic Center. My map puts this at close to 1.5 miles, rather than 2.4. Perhaps Laura read off the distance in kilometers, and thought that they were miles. This alone would lead to a roughly 50% overestimate. However, there were other problems. She estimates that it took people roughly 1 hour to march from Embarcadero to the Civic Center (reasonable), and that a continuous stream of people were marching for 4 hours (less reasonable). Given the assumed distance of 2.4 miles (incorrect, if my map is right), an assumed spacing of people spanned by 20 across (reasonable, and possibly an underestimate) separated along the length of the road by 1 yd (reasonable, but probably too close for an average), she would indeed get 84,000 as the number of people fitting into the stretch of road at a given time. Using 1.5 miles instead of 2.4, this estimate would reduce to about 52,800. The suggestion that 4 times this number actually marched is unreasonable, and is suggested by Laura's own comment that the Civic Center plaza `probably cannot hold more than 50,000 people.' When I arrived along with the last 1/4 of the marchers, it was clear that 1) not many people were in the side streets; 2) few people were already streaming back towards BART or their starting point; and 3) there were not several 10s of thousands of people pushing to get into an overflowing plaza. (The plaza was full, but not overflowing; I had no trouble strolling in and getting to any location I desired.) If indeed 300,000 people were in the process of leaving the scene, the side streets would have been packed (remember, 35,000 people could fill up a broad boulevard such as Market for 1 mile), BART would have been overflowing for hours, and it would have been impossible to enter the plaza by the time my part of the march arrived. As I passed by many places along the march route, there were large numbers of people who were dancing in place, or otherwise stationary. While many people did complete the march route in approximately 1 hour, many did not, reducing by a large factor the average. Some, of course, never completed the course. Reasonable people can argue about the details of these assumptions, but I think that the limited capacity of the Civic Center plaza is the best argument against a total crowd participation in excess of 100,000. In another location on this site, I provide a different set of estimating assumptions, and conclude that the crowd included probably fewer than 70,000, and almost certainly fewer than 100,000. While I am skeptical of official crowd estimates, the S. F. police estimate at 55,000 was not unreasonable for an instantaneous count. (I would guess significantly more overall, with the reasonable assumption that some left before the late arrivals made it to the ferry terminal.)

:: Gross Overestimate, Alas!
by Mark • Tuesday January 21, 2003 at 01:30 AM

:: It would bring me great joy to believe that 1/3 of a million people got their butts out to protest the pending war.

Under ANSWER/WWP's name?

Because whether you like it or not, that is who you all are associated with now.

Just keep up with the news nationally to see why.

I don't think we had (or the police had) any way to tell the number when we're IN it...I was in what seemed to me to be the middle and I never could have GOTTEN into civic center, never saw a speaker or a bumper sticker table. What I did notice, and you must have too, was the way the sound rolled from one block to the next. That was the sound of 5 football stadiums calling to eachother.

I heard an interview about the lawsuit against the park department for their miscount of the million man march which indicated that the only "accurate" way to count is not from the ground OR from a helicopter, but from photographs taken in sequence in a flyover plane. Then the pictures are blown up with a grid and a single grid is counted for density, and multiplied against the number of grids and the margin of error. However, have you read this estimate?

(I hope he forgives my quoting him, especially since i sent links to his post to every major news site...)
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An independent count
by David Chandler • Monday January 20, 2003 at 06:52 AM

I teach physics and math, so I took as my project for the SF demonstration to do my own crowd estimate to see whether the organizers or the media were giving a better version of the numbers.

We arrived early and started our march from Embarcadaro. By 11:00, the nominal starting time, the street was packed to the point where you couldn't easily move around in the crowd without people squeezing out of the way to let you by. Some people who had walked ahead and scouted out the parade route said they had gone 15 blocks and still couldn't see the front of the crowd. They estimated that the entire parade route was essentially filled from the start. It was an hour and a half before we started to move.

My estimate of the stationary crowd density was 500 people for 10 feet along the parade route. That's 1000 people per 20 feet or upward of 10,000 people in the first city block. To make that more conservative, allowing for lack of uniformity, I would allow a factor of 2 margin of error. That makes my initial estimate 5 thousand people in that first block. The blocks don't appear to be the same length, the first one being about 100 m long, but it is easy to see that a 20 block stretch would put the numbers in the 100,000 range.

When I got home I downloaded aerial photographs of Market Street from http://mapserver.maptech.com. Based on the images Market Street is about 34 m across and the parade route was 2.7 km long. This put the total area of the parade route, not counting the square at Civic Center, at 92,000 square meters. For comparison, the first block was about 100 m long, so its area was 3400 sq.m. If we use the 5000 people per block estimate of the crowd density, that makes it about 1.5 people per square meter. If you place a bunch of people 1 m apart you will see this is fairly loose packing, so 1.5 per sq.m is not very far off. Once we got walking the spacing increased somewhat, but not by much. The moving crowd was almost stationary much of the time. It took us about 3 hours to amble a mile and a half.

Using that density for the parade route, not counting the square at the civic center, the count would be 138,000, which I would round down to 100,000, again just to be conservative. The kicker is that when we arrived at the civic center there was an announcement that the end of the parade was back where we had started! In other words we filled the parade route twice. 200,000 people is not at all out of line.

With numbers like these, news reports of "10's of thousands" (CBS, SF Chronicle, etc.) come across as pretty blatant counter-movement propaganda, especially considering that the news agencies had helicopters. Reports that ranged from 100,000-250,000 (which I understand included some of the major media outlets) seem to be honest efforts, but I would go with numbers in the 200,000 range myself.

The numbers were only one piece of the picture. The major contribution of the rally was bringing the West Coast branch of the peace movement together in a very positive, upbeat atmosphere. It was very uplifting. On the other hand, we apparently live in a time when many of those who would like to rule in our name don't count bodies any better than they count votes.
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Just some food for thought.

Heidi