This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

As Sen. Kirsten Gillibrand’s senior adviser for national security, I spent a lot of time getting to know the vigilant, behind-the-scenes-work of the New York City Police Department to keep New Yorkers safe from planned terrorist attacks.

Mothers and fathers raising families in New York City see NYPD efforts first hand — but also see the strength and resilience of everyday New Yorkers that flies in the face of those who would frighten us. This human resilience comes, in large part, from living and working together in urban environments. Neighbors constantly interact in apartment buildings and say hello to small shop owners while running errands, parents rub shoulders with other parents on the playground, and commuters recognize and smile at familiar faces on their bus routes.

Over time, those small interactions build up into a connective tissue that binds us together. This week, in the wake of the terrorist incident in Tribeca, New Yorkers witnessed this connective tissue at work.

Neighbors and acquaintances who know each other simply because they drop their kids off at the same school buses quickly turned to each other to alert family and friends, offer to pick up kids stuck at school and generally offer emotional support. Friends texted and called each other to check if everyone was safe, and to see whether anyone needed a hand. Parents told their children: Don’t be scared, be aware of your surroundings, but focus on the network of support we rely on as New Yorkers. And kids and adults alike turned out for Halloween trick-or-treating, even downtown — not to mention the Halloween parade.

“To change plans would be unacceptable,” said one New York resident, a sentiment echoed by the mayor and governor alike.

So as New York prepares this weekend for one of our celebrated traditions — the New York City Marathon — the NYPD is surely carefully preparing for potential risks. But equally true is that the diverse communities across New York’s five boroughs and those who visit us will greet complete strangers as they cheer the runners and offer them snacks and water.

As New Yorkers, we’ve been building and nurturing this connective tissue for a long time. Anyone who lived in downtown Manhattan during 9/11 remember to this day the feeling of being all in together as complete strangers would pause at the local elementary school where kids had hung up thank yous to the local firemen, many of whom perished while working to save others.

We grieved as a collective, surely helping us through an attack that impacted every New Yorker, whether or not working in the Twin Towers.

And it’s not just in New York where you see this kind of resilience at work. In Boston, after the marathon bombing in 2013, people reached out across all sorts of social and economic divides. In the immediate aftermath of the incident, passersby ran to help and Bostonians opened their doors to those needing a place to rest. As the city worked to heal, having these memories of resilience and community support seemed to make the struggle just a little bit easier.

From Orlando and Las Vegas to Paris and Manchester, there are innumerable stories of cities filled with people who didn’t know each other but who felt compelled to support and offer help in the wake of deadly attacks. Manchester residents tweeted out offers of a lift or a room; Orlando communities donated blood; and in Paris, they hugged and showed up to pay their respect.

In other words, in the face of tragedies that have threatened to cleave cities down the center, the resilience of urban environments has stitched these same communities right up. This resilience of cities has been documented — by books such as Larry Vale’s and Tom Campanella’s “The Resilient City” and elsewhere — as critical in the wake of both terrorism and natural disasters, and methodologies have been crafted to support and deepen urban networks.

This is what New Yorkers most celebrate about our city — and what is so compelling about cities in general: As urban dwellers, most of us are not isolated. The very nature of city life forces residents to connect, and it gives communities a scaffolding to lean on when a disaster hits.

This busy and multifaceted environment also brings many different types of people into one ecosystem — hopefully preventing us from lapsing into reliance on stereotypes, because neighbors lend a hand — despite not looking, living, or praying the same way.

New Yorkers are savvy – and thus will be vigilant, during this weekend’s marathon and in the future. But that will not mean that the city will turn in from fear, but rather we will turn out in celebration, together. This is what great cities do — and this is what builds the connective tissue that makes us resilient.