If you graph out the number of births in the United States every year, one of the things which jumps out is that the 1970s (when many Gen X people were born) had the lowest numbers of births in the last sixty years.
|United States Births by Year|
Throughout this entire period, the total US population was growing, but this was a period when the birth rate (the number of babies born divided by the number of thousands of population) had just fallen significantly from ~25 in the 1950s to ~15 in the 1970s. The rate has been moderately stable since then, but it took a while after the initial drop in birth rate for the growth in the population to catch up and start producing numbers of births per year equal to what was normal before.
The number of births per year translates pretty directly into the number of 18-30 year olds you that you have entering the workplace, because everyone who is 18-30 has to have been born. This means that in the 1990s and early 2000s there was a significant dip in the number of 18-30 year olds.
From 1989 to 2001 the number of 18-30 year olds dropped 14% while the total US population increased by 15%. Then, the number stared climbing again, so that from 2001 to 2016 the number of 18-30 year olds increased 17% while the US population increased only 14%.
The demographer's argument was that the smaller Gen X generation benefited from being a scarce resource. With fewer young people coming into the workforce they had higher employment rates and higher pay -- the 1990s boom -- but that by 2005-2010 you had more young people coming into the workforce each year with an economy going into recession that had already adjusted to get by with fewer entry level workers and less affordable entry level housing. The Millennials were a more plentiful resource than the Gen X-ers and so the economy payed less for them.
There are interesting elements to this, and others that I want to think through more. I hadn't realized that the number of 18-30 year old was growing faster than population at the same time the recession was hitting, and I can certainly see how that would tie in with youth unemployment, skyrocketing higher education costs, etc. We'd now hit the end of that rise and will see a basically flat number of 18-30 year olds for the next ten years while the overall US population continues to increase. That may ease some strain for the next cohort of young adults coming along.
Of course, the trick is that an economy does not have just a set number of jobs for people at a given stage of life. People create innovation, growth, etc. and so in general a healthy economy is one with a growing population. It would be a mistake to see a growing number of young people as a necessarily bad thing for an economy or a culture. And yet, change is messy and systems are slow to adjust. I could certainly see how after twenty years during which the absolute number of young adults shrank or was flat, to have it start growing (and doing so faster than the population as a whole) would throw off a lot of things until people adjusted.