For ponds, she says, it might be that the presence of a certain type of newt tells you whether or not the water is healthy. In cities, the newts are children. “If you can see children, it’s probably a healthy and happy city.”
Large [presumably US] Cities With the Lowest Share of Families With Children
San Francisco 16.5%
Seattle 18.7%
Washington, D.C. 18.9%
New Orleans 20.7%
Miami 21.4%
Minneapolis 21.8%
Philadelphia 22.5%
Portland 23.2%
Denver 23.3%
Cleveland 23.7%
Large [presumably US] Cities With the Lowest Share of Families With Children
https://www.citylab.com/life/2019/01/top-cities-for-families...