Demographics may or may not be destiny. How you define destiny might be worth taking a look at. Demographics, simply defined, is the study of people patterns. Destiny means a lot of things to a lot of people.

Sheer mass of a population is no guarantee as to the size of a market by volume, nor its magnitude in dollars, nor the profitability of the its business participants.

Once, back in the day, when the post-World War II Baby Boom in the United States brought about a previously and subsequently unequaled birth rate, and that combined with the most important macro-economic change of the 1900s--the phenomenal economic supernova of the two-income household--demographics suddenly got an awful lot of credit for business destinies.

We may have gotten used to overstating--understandably--the economic importance of the Baby Boom by conflating the impact of the generational cohort's coming of age with the effect of women's game-changing embrace of employment outside the home. Fact is, the phenomenon of the married-working-couple-with-children household had more to do with our "expanding pie" economy in the 1980s, '90s and early 2000s than the mere size of the Boomer cohort.

What's more, the dual-income household we now take as a given has done a pretty good job of obscuring a "shrinking pie," idling economy.

All that said, here's the way the Census diagrams the population by age structure, as part of its recently updated population estimates by age, sex, race and Hispanic origin for the nation, states and counties.

U.S. Census population data

Here's commentary on the population pyramid from U.S. Census statistician and demographer Luke T. Rogers:

Why do the age groups have different size populations? Let’s examine the baby boom generation (50- to 69-year-old population). During the baby boom, the U.S. population rapidly grew because of high fertility rates following World War II. This population surge is reflected in the U.S. population pyramid as an outward bump in those baby boomer age groups. As the baby boomers grew up, many had kids of their own. The children of these baby boomers, frequently called the echo boomers or millennials, can be seen as a similar bulge in the 15- to 34-year-old population. Even with lower fertility among baby boomers compared to their parents’ generation, the birth of the millennials still represented a mini population boom, simply because there were so many potential boomer parents.

Census Bureau population data

Speaking of boomer parents, do you want to know where the oldest Boomers are, and where they're not? Here's a Census Bureau graphic that will tell you the "oldest" and the "youngest" U.S. counties by percentage population of 65-and-over, and 30 or less.

Census Bureau data on population and age.
The most common ages in 2020; With permission from Calculated Risk's Bill McBride

Importantly, for those in housing, the numbers foretell a brightening scenario on households and demand. Calculated Risk's Bill McBride expresses it this way in his own analysis of Census Bureau population data and projections, which plots the most common ages by year for 2010, 2015, 2020, and 2030. McBride's focus is on the fact that the "population in the prime working age will be increasing," writing:

Note the younger baby boom generation dominated in 2010. By 2015 the millennials are taking over. And by 2020, the boomers are off the list.

My view is this is positive for both housing and the economy, especially in the 2020s.

Working-couple households with young children may not be the sudden juggernaut they were in the late 1970s and 1980s and '90s when they burst on the economic scene for the first time, revolutionizing household needs and household means. But they will return as an economic engine--particularly as mid-30-year-olds form households together, shed college debt and make families.

As stated above, the sheer numbers will not guarantee good times for one residential developer or builder or another, and most certainly will not be the "tide that raises all ships." Instead, the people patterns around work choice, proximity to jobs, use of time, and educational attainment will serve as the more or less evident windows of opportunity and risk. For no doubt, consumers and what prompts them to spend are a moving target. Otherwise, they'd have no leverage at all.