US, China, Japan Population Trends, 1950–2100

About this chart

The picture is the populations of the United States, China and Japan, each drawn as one outline: age bands run up the page, youngest at the bottom, and at each age band the outline reaches left for males and right for females, as far as that group's share of its own population in that year. Each outline's parts always add up to 100%, and the outlines share one scale, so they can be compared level for level. Size is not drawn: the figure with each name is the total in that year. Time is the animation — each frame is one year, and a large generation enters at the bottom and climbs the outline as it ages. A ring marks each outline's largest age band, its two sides counted together, and that age band and its share of the total are written underneath. Every outline is filled, with a thin line between its age bands; an estimate has a solid, lit edge and a projection a dashed one, and the strip under the picture shows where one ends and the other begins. The animation runs the years over thirty-eight seconds, holds on the last for two seconds, and loops. The scrubber pauses on any year, and the speed can be changed in the controls.

Method

Each country's population on 1 July of each year is split by sex and into 21 age bands — 0–4, 5–9 and so on to 95–99, and an open-ended 100+ — and each of the 42 groups is drawn as its share of that country's own total in that year, so every outline's parts add up to 100% and the three share one scale, zero to ten percent on each side. The country's size is not drawn; the figure under each name is its total population that year, the sum of the 42 groups, in whole millions, and the percentages beside Male and Female are each sex's share of that total. The largest age group named under each country is the age band with the largest share of that total, males and females together; the ring marks it on its longer side. The figures are the United Nations' World Population Prospects 2024, population by five-year age group and sex, in thousands: the years 1950 to 2023 are the United Nations' estimates, and the years 2024 to 2100 are its medium-variant projection — one scenario of several it publishes, not a measurement — which is why the outline is lit and filled to 2023 and dashed and unlit from 2024. The series begins in 1950, the first year the source covers, for all three countries. In the source's own words, for statistical purposes the data for China do not include Hong Kong and Macao, Special Administrative Regions of China, and Taiwan Province of China, and the data for the United States of America do not include American Samoa, Guam, Northern Mariana Islands, Puerto Rico, and United States Virgin Islands. The United Nations revises the whole series, past years included, with each edition.

Data sources

• United Nations, World Population Prospects 2024 — Population by five-year age group and sex

Updated 2100 (estimates to 2023)

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