A couple of weeks ago, on a leisurely Sunday afternoon, 40 people gathered at a church in Washington Heights for a show-and-tell session sponsored by the New York City Preppers Network. One by one, they stood in front of the room and exhibited their “bug-out bags,” meticulously packed receptacles filled with equipment meant to see them through the collapse of civilization.

Onto a folding table came a breathtaking array of disaster swag: compasses and iodine pills, hand-cranked radios and solar-powered flashlights, magnesium fire-starters and a fully charged Kindle with digital road maps of the tristate region. Many of the items on display went far beyond the “10 Basic Pillars of Bug-Out Gear” that Jason Charles, the network’s leader, had passed out in advance through the Internet. A good number were tweaked to fit their owners’ needs and interests. A locksmith in the group had a lock-picking set. A vegetarian had a stash of homemade dehydrated lentils. One man had a condom designed to serve as an emergency canteen; another had a rat trap — to catch and eat the rats.

After showing off his own bag (parachute cord, a bivy sack, a two-week supply of Meals Ready to Eat), Mr. Charles, a New York City firefighter, told the group that he had just bought a dog. “So now I have to implement his plan, too,” he said a little worriedly. With a pause and a sheepish look, he added, “That’s weird, right?”

New York hardly seems like a natural location for what has become known as the prepper movement, but in fact the city’s prepping community is not only large and remarkably diverse, its leaders say, it’s also growing rapidly.