Like most people, I’m thinking of the terrorist trauma in Paris, though with a somewhat different perspective. I was in New York on Sept. 11, 2001, and my thoughts go in this direction: What is the future of cities in which psychopaths have killed crowds of bystanders?

In New York, the future as we’ve known it so far has been one of glory and growth. In Paris — its post-attack future just a few days old — it has been a quick return to the previous embrace of culture and camaraderie. The people now thronging the cafes and theaters may be exhibiting more an air of resistance than gaiety, but rest assured that the real enjoyment will take over.

But the aftereffects do not end there. These massacres are not like a wound that eventually heals. They’re more like a cancer that can go into remission for a while and then come back. And these cancers can take on different forms, changing the people in different ways.

The 9/11 attacks in New York were centered on the World Trade Center twin towers, emblems of America’s economic might. They were assaults from above, and the perpetrators were foreigners. Though the weapons were hijacked commercial airliners, the attacks had the feel of a conventional war.

In both cities, it took a while before people felt confident that the onslaught was over. Fourteen years ago, New Yorkers kept looking skyward at every sound of aircraft long after they recognized that the only planes flying over Manhattan were U.S. military.

Manhattan is an island and was eerily cut off from the rest of America. Bridges and tunnels closed. There were no domestic flights, no intercity buses, no Amtrak. For a while, only one or two subway lines were running. Restaurants stayed open, their hardworking staffs at the ready, but only a few stragglers showed up for dinner.

Gradually, all came back to “normal” — more than normal, actually, given today’s congestion, soaring home prices and hyper-expensive eateries without an empty seat.

Although the New York attacks were far grander in scale and horrific imagery, the terror in Paris took on, in some ways, a scarier form. It skirted the national symbols, aiming at places where ordinary people go for fun. These were soft targets, as were the London subway and Madrid commuter railroad, both of which had suffered terrorist bombings.

In New York’s landmark Grand Central Terminal, heavily armed troops patrol the marble floor. The subway lines jammed with people are not so protected. New York would grind to a halt were residents and visitors afraid to ride the subways. And New York police are on alert as the holiday season fills the great stores, cabarets, dance clubs, theaters and surrounding streets with humanity.

We have no idea in which direction the terrorists’ demented imagination will next turn. They seem to value surprise and may afflict smaller cities. In Europe, they already have. They may go after food and water supplies, a scenario the U.S. Department of Homeland Security is already considering.

What we know is they won’t go away any time soon. The Paris attacks were against ordinary people, and the ordinary people have returned to their soft-target hangouts in defiance. Whether they would continue to do so after multiple incidents remains to be seen.

But one would hope the people of New York — or any other American city subjected to terrorist mayhem — would emulate the resilience of Parisians.

America’s city-loving millennials remain untested, but they’re a tough lot. Let’s pray they never have to go through this, while having faith they would do so bravely.

Froma Harrop is a syndicated columnist. Follow her on Twitter @FromaHarrop. She can be reached at fharrop@gmail.com.