Crowd counting
Encyclopedia
Turnstile
A turnstile, also called a baffle gate, is a form of gate which allows one person to pass at a time. It can also be made so as to enforce one-way traffic of people, and in addition, it can restrict passage only to people who insert a coin, a ticket, a pass, or similar...
s are often used to precisely count the number of people entering a venue. At unticketed events, especially events that take place in the streets or a park rather than an enclosed venue, crowd counting is more difficult and less precise. For many events, especially political rallies
Demonstration (people)
A demonstration or street protest is action by a mass group or collection of groups of people in favor of a political or other cause; it normally consists of walking in a mass march formation and either beginning with or meeting at a designated endpoint, or rally, to hear speakers.Actions such as...
or protest
Protest
A protest is an expression of objection, by words or by actions, to particular events, policies or situations. Protests can take many different forms, from individual statements to mass demonstrations...
s, the number of people in a crowd carries political significance and count results are controversial. For instance, the global protests against the Iraq war saw many protests at which widely differing counts were offered by organizers on one side and the police
Police
The police is a personification of the state designated to put in practice the enforced law, protect property and reduce civil disorder in civilian matters. Their powers include the legitimized use of force...
on the other. Another memorable incident occurred when Louis Farrakhan
Louis Farrakhan
Louis Farrakhan Muhammad, Sr. is the leader of the African-American religious movement the Nation of Islam . He served as the minister of major mosques in Boston and Harlem, and was appointed by the longtime NOI leader, Elijah Muhammad, before his death in 1975, as the National Representative of...
threatened to sue
Lawsuit
A lawsuit or "suit in law" is a civil action brought in a court of law in which a plaintiff, a party who claims to have incurred loss as a result of a defendant's actions, demands a legal or equitable remedy. The defendant is required to respond to the plaintiff's complaint...
the Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
Park Police for announcing that only 400,000 people attended the 1995 Million Man March
Million Man March
The Million Man March was a gathering of social activists, en masse, held on and around the National Mall in Washington, D.C. on October 16, 1995...
he organized.
Jacobs's Method
The most common technique for counting crowds at protests and rallies is Jacobs's Method, named for its inventor, Herbert JacobsHerbert Jacobs
Herbert A. Jacobs was a journalist for the Milwaukee Journal and later a professor of journalism at the University of California, Berkeley.-Houses:...
. Jacobs method involves dividing the area occupied by a crowd into sections, determining an average number of people in each section, and multiplying by the number of sections occupied. According to a report by Life's Little Mysteries, technologies sometimes used to assist such estimations include "lasers, satellites, aerial photography, 3-D grid systems, recorded video footage and surveillance balloons, usually tethered several blocks around an event's location and flying 400 to 800 feet (120 to 240 meters) overhead."