The crowd showing up Jan. 20 for the Obama inauguration could be the largest in U.S. history, according to some news reports. Estimates have run as high as 4 million. Clark McPhail, a professor emeritus of sociology at the University of Illinois, knows that size estimates before, during or after an event usually are "guesstimates," and often hugely inflated. The author of the book "The Myth of the Madding Crowd," he has been studying crowds and crowd behavior since the 1960s, and advising people who manage them. McPhail was interviewed by News Bureau social sciences editor Craig Chamberlain.
Just how many people can Washington reasonably accommodate for its inauguration day events?
Up to 240,000 ticket holders will be seated on the West Lawn of the U.S. Capitol and a portion of the National Mall for the inaugural ceremony and 9,000 bleacher seats are reserved along the Pennsylvania Avenue parade route. Any plausible estimate beyond those known numbers requires answers to three questions. What is the square footage of the available public space? What proportion of that space is occupied? What is the density ratio of that occupation? Those three variables are the core of the U.S. Park Police method for estimating gathering size. [U.S. Park Police official counts of Washington, D.C., events were discontinued after 1996.]
The remainder of the National Mall extending west from the Capitol to the Washington Monument grounds can accommodate 450,000 people. One-third of the Washington Monument grounds face the Capitol; the remaining two-thirds, known as "the West Slope," can accommodate 231,000 people. People in these areas will see and hear the inaugural ceremony and parade on multiple mega-television screens and hundreds of loudspeakers. The available sidewalk spaces bordering along the Pennsylvania Avenue parade route can accommodate 27,000 people. With all those numbers taken into account - 249,000 people seated and an estimated 708,000 standing - we get a total of 957,000. Comparable occupancy of the Lincoln Memorial grounds could accommodate an additional 250,000 people standing and push the estimated total to 1,207,000. This is all assuming a density of 5 square feet per standing person. If you increase the density to 2.5 square feet per standing person, this would boost the total to 2,115,000. However, it is unlikely that this many people could safely or comfortably remain in such limited space for the several hours prior to and throughout the inaugural ceremony and the parade in what will likely be very chilly weather.
What factors are involved, and mistakes most often made, in estimating the size of large gatherings?
The first factor is the ego or pride of those political activists or public officials who have worked diligently to organize and mobilize participation in the gathering. Bigger is better in our culture, and thus organizers are likely to exaggerate gathering size as evidence of its significance. The second factor is the vantage point from which an observer views and estimates the distribution, density and size of the gathering. Large gatherings are usually more densely packed at the front and middle than at the back or sides. Estimates made from the front of the gathering and from a vantage point at or near ground level are victim to the perceptual illusion that the entire gathering is as densely packed throughout as it is at the front. This leads to the erroneous conclusion that the gathering is much larger than it more accurately appears when viewed from overhead. Organizers on a stage, looking at the gathering spread out before them, often fall victim to this illusion. So do inexperienced police observers and journalists. The U.S. Park Police take digital photos from their helicopter flying directly above gatherings.
We often picture a crowd as a collection of individuals all thinking or acting alike, capable of being easily swayed by a dynamic speaker, or "turning ugly" or uncontrollable. Based on your research, what's wrong with that picture?
First, the word "crowd" implies a uniformity of individual members, their motives and their actions that's contrary to the facts. Many will come to this inauguration to praise the president, many others to protest or advocate on multiple issues, others to sell souvenirs, food and beverages, others to record and report, still others to protect. Second, most individuals assemble for most gatherings with one or more family, friends, or acquaintances with whom they remain throughout and with whom they disperse. Thus most gatherings are composed primarily of small primary groups whose members exercise more control over one another than any "dynamic speaker" or even a police officer. Third, uniformity of actions is extremely rare in any large gathering. Systematic observation data show the most characteristic feature of most gatherings is alternating and varied individual actions, interactions with companions, and collective actions. This lends more credibility to a picture of the individual as a self-organizing and self-directing actor.
Do people ever truly lose control of themselves in a crowd? If not, how do you explain mobs and riots?
The question assumes a crowd or mob mentality. Those concepts are long-standing myths created and perpetuated by arm-chair psychologists and sociologists who have not spent time in the streets looking at and listening to what people actually do and say. Most people gathered in a riot area are onlookers. Only a minority engages in violent acts against persons and property, and do not do so continuously or exclusively. Most violent acts - vandalism, looting, arson - are selective and deliberate. Individual loss of control is rare, even in such life-threatening situations as fires, floods, explosions and airplane crash landings. Individuals are more likely to look after one another than to act in self-serving and foolish ways. There are two viable explanations for most instances of loss of control: excessive consumption of alcohol or other drugs, which impairs individual perception and decision-making; and very-high-density gatherings that physically constrain the ability of individuals to control when and where they can move.