Skip to Main Content

Arithmetic, Numeracy, Literacy & Imagination: A Research Guide

Crowd Counting & Estimation

Inauguration of Abraham Lincoln - March 4, 1861 c.1935. Library of Congress Prints and Photographs Division.

Numeracy, defined as the capacity for quantitative thought and expression is frequently used in business transactions. when teaching children how to count, we often develop mental arithmetic skills using a variety of sources to include flashcards, charts, etc. How is this acquired skill set to translate into counting crowds? There are several approaches or strategies used to determine these numbers or estimates. Inauguration crowds tend to have thousands, sometimes hundreds of thousands of attendants, and it becomes difficult to determine the numbers. Here is where numeracy comes in. Counting crowds sounds like a simple task, but it is more complex than it seems. One of the main reasons it is done is for crowd safety and creating routes for crowds to exit different areas in case of emergency. It can also be used to predict the size of future gatherings, ensuring that business models are in place to include transportation, availability of food, etc. From a business standpoint, articulating expected crowds identifies a further analysis of demand and supply and thus allows business owners to be more equipped.

Counting and writing numbers, or numeration and notation. 1890. Popular and Applied Graphic Art Print Filing Series. Library of Congress Prints and Photographs Division.


For the past two centuries, different techniques have been used to calculate the number of people in a crowd, from photographs and grids to satellite images. Taking a look at presidential inaugurations where thousands of people usually attend, scientists can calculate the number of people present using a grid and identify the area and density used up by each person. Early texts from the 19th century reveal numeracy as a pathway to logical thinking as evidenced in word problems. Instruction was given to young children in solving problems unique to the family farm, small businesses, the measurement of cloth, and other wares. A simple word problem such as: A gardener set out 30 peach trees, in rows, putting 5 trees in a row. How many rows were there? (Emerson, F. 1840), was used to train children in mental math which would allow them to use their imagination, and which gave them the ability to perform simple calculations using arithmetic. This methodology created a way for them to come up with answers. Crowd estimates were calculated in a similar manner where mental math and imagination are intertwined to compute the number of attendees. For example, given specific square footage that would encompass a certain amount of people, density, and area are put into consideration in order to determine the numbers of large crowds.

Maureen Keating, photographer. Aerial view of marchers on the National Mall during the Million Man March, looking towards the Washington Monument. Oct. 16, 1995. CQ Roll Call Photograph Collection. Library of Congress Prints and Photographs Division.

Numeracy plays a big role in the lives of data journalists, geographers, and demographers who research and culminate large crowds such as inaugurations. There are several approaches or strategies used to determine the quantities. Topography comes in handy when calculating spaces because it studies the shape of the surface of an area. For example, if an image is taken at an angle of a hill, the number of people may seem more than there actually are. Density maps are often used to determine numbers at these events which provides a more accurate calculation for events such as inaugurations, concerts, protests, and so on. Density maps use dots to represent the number of people in a given area. Aerial photographs that can be taken by satellites or helicopters provide a visual of an area.


The following titles link to fuller bibliographic information in the Library of Congress Online Catalog. Links to additional online content are included when available.