The Cheddar Revolution: How Many People Attended the Rally in Chicago?

The Chicago Tribune reports that “several hundred protesters” showed up to support Wisconsin workers yesterday. ABC7Chicago said “hundreds” showed up in solidarity with public employees. The local CBS affiliate said the crowd numbered in the “hundreds.” The Huffington Post boldly proclaimed “more than a thousand people” were there. Even the Democratic Socialists (who knew?) put the crowd at a mere 2,000.

Was I wrong in my estimate? Sure. I’m no expert in this stuff. Was I that wrong? I don’t think so. So I did some thinking and some poking around to try to figure out where I got the idea that several thousand protesters – not several hundred – filled the plaza at Chicago’s Thompson Center yesterday.

I figured I needed to find out the area of that plaza before I could figure out how many people could fit into it. So I got the latitude and longitude coordinates of the roughly triangular plaza of the Thompson Center using Google Earth. I then calculated the area of the plaza at the Thompson Center using the Google Maps Area Calculator Tool. The highlighted area (click on the map to see it full size) where the rally took place constitutes 33,940.38 feet². Let’s be conservative (so to speak) and round it off to 30,000 square feet.

According to the Poynter Institute, working to improve American journalism since the 1970s, crowd estimates are difficult, but not impossible:

A loose crowd, one where each person is an arm’s length from the body of his or her nearest neighbors, needs 10 square feet per person. A more tightly packed crowd fills 4.5 square feet per person. A truly scary mob of mosh-pit density would get about 2.5 square feet per person.

The trick, then, is to accurately measure the square feet in the total area occupied by the crowd and divide it by the appropriate figure, depending on assessment of crowd density.

So by this rule of thumb, in 30,000 square feet of space a loose crowd would consist of about 3,000 people. A more tightly-packed crowd would contain more than 6,000 people, and a truly dense crowd, jam-packed into 30,000 square feet, could easily be close to 12,000 people.
Now this was a pretty tightly-packed crowd at yesterday’s rally, but it wasn’t 12,000 people. But I think my initial estimate of between 5,000 and 6,000 people is pretty close.

So why are the local media reporting that “several hundred people” showed up?

The Cheddar Revolution

A Rally in Support of Wisconsin's Public Workers from Dr Fallon on Vimeo.

Chicago went all Cairo today on Wisconsin Governor Scott ("I've got a baseball bat in my office") Walker as thousands of residents of the Windy City showed up at the State of Illinois Building (The Thompson Center) to protest Walker's cheesy, sleazy attempt to take away collective bargaining rights from state workers (translation: to break unions).

I'm not really very good at such things and I claim no true expertise, but I have had a little experience looking at crowds and figuring out how big they are, and I can tell you this: this was a BIG crowd.

The video gives only a flavor of the rally; I was too far from the podium to either see or hear the speakers very well (although I was glad to see my Senator, Dick Durbin, showing solidarity with the crowd) so don't look for speeches. But I spoke to several people to ask them why they were there. None of them were paid by wealthy ideologues to attend. They wanted to be there. Take a look and a listen.