“I don’t hear birdsongs in the morning, like I did when I was a kid,” said Jim Stone, executive director at Walk San Diego. “They’re slowly going away. Things in our lives change, but because they change in slow increments over a long period of time, we become accustomed to what’s new.”

Stone and I weren’t actually talking about birds. We were talking about walking and walkability in America. About how our access to places on foot alters subtly from one generation to the next, almost imperceptibly. “What we witness and what we encounter becomes the new status quo, the new benchmark in how we make assessments,” Stone said. “If people would remember a time when they could walk freely, they could make a comparison. The problem is, that time is getting further away from us.”