Math Science Tech

How are crowds counted?

On this special National holiday, it’s impossible not to reflect on Dr. Martin Luther King, Jr. and the famous speech he delivered to a crowd of over 250,000 civil rights activists and supporters in Washington, D.C. in 1963. With the BLM protests this summer, MAGA rallies during election season, and the upcoming Inauguration this week, the Hot Girls got to thinking… How are massive crowds counted?

View from the Lincoln Memorial on August 28, 1963 – U.S Government Photo

Herbert Jacobs developed the most common method used to count large crowds while teaching journalism at UC Berkeley in the 1960s. After witnessing numerous campus protests against the Vietnam War from his office window, Jacobs noticed that the plaza the students occupied resembled a grid. He deduced that by splitting the larger region into smaller sections, one could estimate the total crowd size by figuring out the average number of persons in those sections based on crowd density and then multiplying that figure by the number of remaining areas.  Thus the “Jacobs Method” was invented.

Jacobs Method = Area x Density

While studying these campus gatherings, Jacobs began to notice patterns in crowd density, which aided in determining how packed the areas being counted were:

  • Light crowd ~ 10 sq ft per person (enough room for people to stand at arms width apart)
  • Manageable crowd ~ 4.5 sq ft per person (comfortably standing shoulder to shoulder)
  • Tight crowd ~ 2.5 sq ft per person (referred to as mosh-pit density, it is the limit before a group becomes dangerous with a risk of participants being trampled)

Modern technology has undoubtedly aided in crowd counting through high-resolution photography and drone footage; however, these visual aids are used to enhance the Jacob’s Method, as it remains the most widely used application to determine crowd size today.

Hot for more? 

READ: The Curious Science of Crowd Counting

WATCH: The Delicate Science of Counting Crowds

Feature photo by Alex Radelich via Unsplash

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