ACTION-ORIENTED ACTIVITY 2.3: Bar Hopping Around The Pyramids
INTRODUCTION: Population pyramids (also known as age-sex pyramids) are specialized bar graphs that display an area's population by age and sex (gender) for a particular point in time. Pyramids are usually standardized to display the male population age brackets on the left side of the graph, female population age brackets on the right, younger age brackets at the bottom, and older age brackets at the top. Ideally, five-year age brackets are shown (e.g., ages 0-4, 5-9, 10-14, etc.). Pyramids have the top bar on each side of the graph represent some cutoff point age-bracket (e.g., sixty-five and above, seventy-five and above, etc.). The bottom of the graph is typically scaled to read the bars as percentages of the total population, or sometimes the actual number of people is shown on the scale, which is the case for the United States age-sex pyramid. If the bars are scaled to represent percentages of the total population, which is preferred in this virtual field activity, places of all population sizes can be easily compared (e.g., Canada and China), since the sum of the lengths of all the bars for each area examined will be the same (i.e., 100%). The term "pyramid" is used because, historically, most areas typically had a large young population, a somewhat smaller middle-aged population, and an even smaller older population. Therefore, the graphs were usually quite broad at the base, and tapered steadily to a narrow peak, just as a true pyramid is shaped.
You will see that in today's world, population pyramids for different countries, states, and cities show a myriad of shapes. Most of the developing nations today still have age-sex graphs that are shaped like a pyramid. However, some of the more developed nations in Western Europe have shape profiles that are almost vertical, meaning that no one age cohort dominates the graph. The age-sex graph representing the state of Florida will be "top heavy" due to its large retirement population, whereas Utah's pyramid will have a much broader base reflecting the relatively high birth rate among the Mormon population, which represents a majority of the state's residents. One could construct a single population pyramid for an entire city, which would have a particular shape, or produce a dozen or more differently-shaped population pyramids showing various neighborhoods within the city, which also may be differently-shaped. Neighborhoods with colleges, prisons, military bases, retirement communities, and Veteran Administration hospitals reveal considerably different demographic profiles than a residential community.
Start your field work by visiting the Web site for US Census information.
Once there, select Population Pyramids. Here, countries are located alphabetically. Pyramids are available for various time periods, depending on the country chosen. Under "Type of Output," students can choose either "summary" (pyramids for 1997, 2025, & 2050), select years (e.g., pyramids for the United States for every year between 1950 and 2050), or dynamic (and visualize a country's population as the pyramid changes from year to year up to the year 2050). Please note that population pyramids can be important planning tools because predictions can be made regarding such impacts as certain age cohorts on school enrollments, work-force size, health concerns of an aging population, and retirement issues.
Let's compare the "summary" pyramids for the United States, China, Germany, and Bangladesh. First, examine the United States pyramid. Locate the bulging "Baby Boom" generation on the graphs (those born between 1946 & 1964). In 1997 they are found in the 30-50 age brackets. When they were in their pre-school years (1946-1970), baby boomers created huge markets for baby products (diapers, cribs, baby food, etc.) From ages 5-18 (1951-1982), they impacted pre-collegiate school enrollments. The past quarter-century is marked by the baby boomers' impact on the U.S. work force.
A.Now, consider the questions below:
The United States
1. What are some of the likely impacts baby boomers will have on American society when they retire and achieve senior citizen status?
2. Why do females continue to outnumber males in the older brackets?
China
1. Why do Chinese men greatly outnumber women, particularly at the younger age brackets?
2. What do you think caused the large indentation in the 35-39 age bracket in China's 1997 population pyramid?
3. Why does China's 2025 pyramid look so markedly different from the 1997 pyramid?
Germany
1. What do you think caused the large indentation in the 50-54 age bracket in Germany's 1997 population pyramid?
2. Is Germany's total population expected to decline between 1997 and 2025 and beyond?
3. Which bracket is predicted to be the largest for Germany in 2050?
Bangladesh
1. Why is its 1997 pyramid so different from the U.S. and Germany pyramids?
2. How many people in Bangladesh were under age 5 in 1997?
3. Is Bangladesh's population expected to exceed 200 million in 2050?
B.The U.S. Census Bureau Web ( also features "population clocks," which display its estimated population totals for the United States and the world at the moment you log on! Check from one day to the next to note any changes. On August 2, 1998, the estimate for the population of the United States was 270,259,165. The World Population Estimate on that date was 5,933,543,609. How have the numbers changed?