age cohort size and population distribution

[Linus Van Pelt]

The following graphic appears in a Census Bureau publication about age distribution in the 2010 census. The solid blue represents the age distribution in 2010, while the dotted lines represent it back in 2000.



As you can see, in 2010 there is a significant gap at about 64 representing the start of the postwar baby boom around 1946/7. Then the height of the baby boom appears to be about 50, while there is another peak around 19/20.

This means that the population is on the cusp of some major changes. Over the next little while, the percentage of seniors is going to increase to a level that has historically not been seen. And also, whereas the number of people in their mid-to-late 20's was fairly low until recently, it is going to be quite high over the next decade.

Now, it seems to me there has been a bit of a shift in population trends over the past couple of years. In the 2010 census the motion both to the sun belt and within metros to the suburbs remained quite strong, and a widely-rumored return to the city cores was fairly weak in most places. In recent estimates, however, migration to the sun-belt has continued but within northern and west-coast metros much more of the growth has been in city cores.

It also seems to me fairly likely that these are connected, and are likely to continue. In the case of seniors, it strikes me (contrary to what some have predicted here) as fairly unlikely that the growth of the sun belt will see a significant decline any time soon with the increase in the 65+ population that is about to hit us. And I would also suggest that the start of a rise in the 23-30 demographic is a significant part of the explanation of why many metros are seeing less suburbanization than they did over the 2000-2010 period.

We shouldn't over-stereotype; many seniors would rather live in their home town than in Florida, and many 20-somethings would rather buy a house in suburban Houston than some downtown loft. But it's a matter of trends.

[Seattle]

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While I think this is true, this growth will have to take place in regions of the sun belt with adequate water (Gulf of Mexico, Florida). Eventually, water issues will cap growth in Arizona, New Mexico, Nevada, parts of Texas, and Southern California.

[muon2]

The cohorts from ages 20-30 in 2010 are significantly larger than they were as ages 10-20 in 2000. That increase is a measure of immigration in the early 2000's.

[Franknburger]

The cohorts from ages 20-30 in 2010 are significantly larger than they were as ages 10-20 in 2000. That increase is a measure of immigration in the early 2000's.

.. and a plausible explanation for the recent inner-city population growth.