The student-to-teacher ratio is one of the things parents consider when judging a school. If you’ve got too many children per adult, parents begin to worry that little Susie won’t get the attention she deserves or that unsupervised boys will form feral gangs that will turn the place into a scene from Lord of the Flies.

On a national level, it seems, that problem has been solved. The United States added millions of adults over the past decade, but we forgot to replenish our children.

“U.S. Adult Population Grew Faster Than Nation’s Total Population From 2010 to 2020,” ran the Census Bureau’s headline. That was an understatement of the demographic shift. The U.S. added 23.7 million adults in the past decade (a 10% increase), while the under-18 population actually decreased by 1.1 million, from 74.2 million to 73.1 million.

Our growing childlessness is visible without even diving into the numbers. Look around and you can see public schools, grades K-12, shuttering their doors, some becoming elder care facilities. Little Leagues are drying up and consolidating with nearby towns.

The effects will be more visible in some parts of America because the loss of children wasn’t uniform nationwide. The South saw its minor population grow by 2.1%, while the rest of the country saw a decline. It was most extreme in the Northeast, where the sub-18 population shrank by 5.1% in a decade, following a 5.5% drop the decade before.

The culture will shift as more adults go through their days without spotting a pre-adult. You can glimpse this future in Europe and a few U.S. cities such as San Francisco. With fewer tykes running around underfoot, you’ll see fewer cheap restaurants but more expensive boozy brunch spots. Minivans will be scarcer. Dog parks will outnumber playgrounds. You won't be able to find an elementary school — but if you need a dialysis center, you'll be in luck.