A year ago, Hurricane Sandy revealed harrowing realities about the basic systems New Yorkers rely on every day. We now know, for example, what happens when fuel supply lines get cut and electricity goes down: mob battles at gas stations and, more terrifying, empty shelves at food stores. Worse, such breakdowns tend to cascade. No power means whatever food is left will rot. No gasoline means delivery trucks can’t restock stores.

It’s a domino effect, one that last year brought New York to the edge of real disaster. According to numerous resiliency experts I interviewed, at the moment Sandy hit, New Yorkers had only about three days of food on hand.

In the months after, city and state officials tended to focus on reinforcing the infrastructure that’s under their direct control. In New York, this means public facilities like Hunts Point Food Cooperative Market in the Bronx, which was forced to shut down temporarily.

Yet as the 9/11 Commission found, some 85 percent of the U.S.’ critical systems on which Americans depend — including those for food and fuel delivery — are controlled by private companies. And the corporations that control these systems have in recent years radically whittled down both the number of warehouses that serve New York and what’s in their contents.

The reality is that private food and fuel systems everywhere are already extremely fragile, and grow more so almost by the day. At best, Sandy-like shocks cause temporary price spikes. At worst, these ruptures can trigger the sort of panic that can forever change the character of a community.