JF

Average age in America in 1835 was *probably* somewhere around 18 years old. The energetic nation he saw, the nation of joiners, was a nation basically devoid of any old elite. I mean literally: there just weren't many old people around to say how things used to be.

Sorry, mixed up a state: 1835 was probably around 20, not 18. Still. The thing you have to realize is France at the time was averaging about 25 years old. The UK was probably around 23/24. Italy and the Nordics were also mid-20s. My point is, America was YOUNG.

The sense that anything was possible and the future was bright was partly driven by the fact that there were just a weirdly large number of enthusiastic young Americans looking to split logs and become President.

Today America is still relatively young. However, during the 1920s and 1930s we suddenly got old SUPER DUPER FAST. This was partly due to falling birth rates. But most countries had falling birth rates at that time. The bigger driver was falling immigration.

But here's the thing: adding more immigrants does NOT make society younger in the long run. Immigrants get old too and their fertility rates converge. Adding immigrants keeps the country younger while inflows are high, but causes rapid aging when inflows fall.

You can see this in the US in the 20s where our average age just rockets up after immigration restrictions. It falls during the Baby Boom, and then has risen smoothly during the period of higher immigration.