Check out the dynamic graph below that represents the US age distribution from 1933 to 2100. It starts as a narrow pyramid with a relatively even age distribution narrowing as it gets to older ages. Then it takes on an arrowhead shape as the dearth of births during the Depression begins to work its way up through the ages.
This quickly changes to more of a spade (playing card, not shovel) as the Depression birth dearth is followed by the 50s Baby Boom. That bulge keeps working its way up the age progression until about now, when the boomerang generation begins to catch up with its parents.
Then the so-called pyramid gets increasingly top heavy. As we move towards future projections, the choppy graph that represents actual people smooths out. The chart creator, Stephen Holzman, then adds colors and shows a broadening range of possible population outcomes in the future depending on the rates of births and deaths. As the so-called pyramid develops, it becomes widest at about age 70, then becomes almost flat at the top as few 70-year-olds make it to age 100.
Conclusions about these population trends
What’s clear is that the average age of Americans is going to keep increasing. What started as a very narrow, sharply-pointed spearhead 90 years ago, with fewer Americans at every extra year of age, will become a blunt wedge 70 years in the future. At the same time, after the Boomers and their children pass from the scene, there will be a more uniform age distribution which should by itself have an effect on how the generations develop and relate. Of course, projections of uniform birthrates may be upset by the reality of booms and busts, or at least boomlets and bustlets. And there’s the effect of higher or lower rates of immigration.
It’s also interesting to note that the huge surge in the US population during the past 90 years will not be repeated over the next 70, at least as projected. The population that was 116 million in 1925, grew to 152 million by 1950, 216 million by 1975, 282 million in 2000 and 349 million today. According to one set of projections, it is projected to grow to about 360 million in 2050, 365 million in 2075 and 368 million in 2100. This slowing growth rate may be better seen in following chart.
| Year | Population | Growth | % Growth |
| 1925 | 115,000,000 | ||
| 1950 | 152,000,000 | 37,000,000 | 32% |
| 1975 | 216,000,000 | 64,000,000 | 42% |
| 2000 | 282,000,000 | 66,000,000 | 23% |
| 2025 | 342,000,000 | 60,000,000 | 21% |
| 2050 | 360,000,000 | 18,000,000 | 5% |
| 2075 | 365,000,000 | 5,000,000 | 1.4% |
| 2100 | 368,000,000 | 3,000,000 | 0.8% |
These projections that the US population will essentially stop growing after 2050 and that we now have almost 95 percent of the number of residents as we will in 2100 depends on a continuing decline in birthrates and no increase in immigration. Any change in either could significantly change these projections.