From:  Imponderables - The Solution to Mysteries of Everyday Life.
by David Feldman, William Morrow and Co., NY, NY, 1987
Presented with permission of the author.
To purchase this book go to: www.imponderables.com

The unenviable task of making crowd estimates usually falls on the local police department, and parades are usually the occasions for these estimates. The most famous parade in the United States, the Tournament of Roses parade, held in Pasadena, California, every New Year's Day, has, since 1930, consistently estimated its attendance at from I to 1.5 million. The Pasadena police would be quite happy not to make crowd estimates, but the press needs figures (it just doesn't sound right to start a newspaper story about the parade by saying, "A whole bunch of people showed up in Pasadena . . ."), and politicians need to measure the success of the parade in order to boast of their accomplishment.

But how are these estimates made? Imagine the logistical nightmare of trying to count heads at a ticker tape parade in lower Manhattan, with its asymmetrical streets, floating debris (obscuring vision), and the staggering numbers involved.

For several years, Michael Guerin, the special events public information officer for the City of Pasadena, has had the responsibility of figuring out the attendance at the Tournament of Roses parade. Guerin flies over the parade site in a helicopter. Obviously, he doesn't count heads. From his years of experience, he knows what 104,000 people look like bunched up together, for that is the capacity of the Rose Bowl, home of the football institution that follows the parade. Using the Rose Bowl crowd as a benchmark, Guerin tries to conceptualize the 100,000+ people he has seen in the circular stadium into the linear crowd along the parade route. This can't be a precise measurement; after all, the parade route spans exactly five and a half miles, and he must also count spectators who look at the floats in the formation areas, where they are assembled, as well as the post-parade area where the floats are put on display.

Since the population of Pasadena is well under 200,000, local officials are used to skepticism about their estimates of 1,000,000 plus spectators, and were challenged in 1983 by Peter Apanel, founder of the Doo-Dah parade, a spoof of the Tournament of Roses parade. Dubious about official estimates, Apanel commissioned photographers to shoot 442 sequenced snapshots of spectators lining the Doo-Dah parade (which that year, police and Apanel agreed, attracted more than 50,000 viewers) at fixed intervals. Apanel then counted every single person in those pictures and extrapolated density levels applicable to the New Year's parade. Although he claimed that for two-thirds of the route, the shorter Doo-Dah parade had as much or more spectator density, he multiplied the density level by two when estimating the Tournament of Roses parade crowd. By factoring in the fans sitting in the reserved bleachers and the longer route of the Tournament of Roses parade, Apanel insisted that the police estimate was way off that no more than 360,000 people could have attended the parade in 1983, or about one-fourth of the police estimate.

Robert Gillette, a reporter for the Los Angeles Times, did a little figuring of his own. He measured the depth of the standing room area at 23 feet, marked on one side by the blue line behind which all spectators must stand and on the other side by the buildings at the back of the crowd. Multiplying this standing room area by the 5.5-mile parade route, Gillette calculated that the parade route provided 1,336,000 square feet (not all of this space was occupied, since attendees toward the back can and often do move about freely, but Gillette did not factor in unused space). He then assumed that each attendee occupied two square feet (one foot thick and two feet wide). Dividing the 2 square feet into the 1,336,000 square feet, Gillette arrived at the figure of 668.000 as the maximum number of people that the Tournament of Roses parade route could accommodate.

Other skeptics have arrived at different estimates, including some Pasadena-based California Institute of Technology professors, who put a half million as the maximum number. Guerin, however, feels confident in his approximation and notes that in the helicopter, he is always amazed how fluid the pedestrian traffic is. In the early morning, it always looks like attendance is bad, but somehow new people keep appearing. Guerin added that although the official Pasadena estimate is hardly precise, it's as good a guess as anyone else's and that police don't receive any kind of special training or education in crowd estimation.

Imponderables spoke to New York officials about how they make crowd estimates. In most cases, the task is left to the local police precinct where the parade takes place.

The police make stabs at accuracy, but it is no more a science in New York than in Pasadena. The most popular technique for Fifth Avenue parades (such as the St. Patrick's Day parade or Columbus Day parade) is to count the number of rows of spectators behind the blue wooden barriers that are placed on each side of the street. Each barrier is fourteen feet long. Assuming that the population behind each barrier will reflect the parade route as a whole, the police estimate how many spectators fit into the square footage available in essence, they duplicate the methodology of Doo-Dah founder Apanel without using photographs, and simply assume that density levels will not vary greatly at different points in the parade route.

Another, more ingenious method of estimating crowd size is by examining the quantity of artifacts they leave behind. To say it less delicately, one way of counting a crowd is to weigh how much garbage it leaves behind. Since sanitation trucks are weighed electronically at the disposal site, it has always been an easy matter to measure the amount of debris left after New York's famed ticker tape parades down the "canyon of heroes."

Counting garbage is not a perfect scheme for measuring crowd sizes, however. The Macy's Thanksgiving Day Parade, for example, is notorious for its large attendance but pitiful lack of garbage, which rarely surpasses ten tons. Even the Tournament of Roses parade weighs in at around a measly forty tons a year. These parades are pikers compared to the ticker tapes, but the latter have the advantage of artificial inflation in recent years, some parade committees have actually imported shredded paper from out of the city to be thrown at passing heroes. Not much ticker tape is thrown anymore. Computer printouts are the replacement. More and more skyscrapers are "climate controlled," with windows incapable of being opened, reducing the opportunities for many to contribute to the mess. All of these factors make it difficult to correlate crowd size with quantity of garbage, but the New York City Department of Sanitation is besieged with requests for the garbage count, and most observers feel there is some connection between the amount of paper thrown and the frenzy and enthusiasm of the celebrants.

For Casey Kasem fans everywhere, here are the top five garbage parades of all time in New York:

5.  1969 Mets parade--1254 tons.
4.  Iranian hostages' return, January 30, 1981--1262 tons.
3. Douglas MacArthur's return, April 20, 1951--3249 tons.
2. John Glenn, March 1, 1962--3474 tons.
1.  V-J Day, August 14, 1945--5438 tons.

Every single source I spoke to about this Imponderable conceded that precision in estimating crowds was impossible and the task itself of less than earth-shattering importance. None was trained to execute this task. And all of them felt that newspapers and politicians would force them to continue with the madness.