This weekend was Halloween. On the streets kids were trick or treating in their colorful costumes and masks, accompanied by their doting parents. It's a reflection of how we live now that they were going from store to store instead of from house to house, to fill their yawning candy bags.

Outside it was unseasonably mild, a welcome change from our usual bone-chilling Halloween nights here in New York. I stepped into a convenience store to buy milk when I overheard this exchange.

"Trick or treat!" shouted some little girls. "Sorry kids, we're all out of candy," came the reply from the store keeper.

There was instant incredulity at this remark. No one can express their disdain with the sheer theatricality of little kids. They screwed up their noses at his announcement and one of them actually said: "But this is America! How can you be out of candy?"

I loved that. I loved that for this child America meant abundance and possibility and satisfaction. Long may it always.

But the shopkeeper, who I thought I knew, said this in reply: "You're not American, you're Spanish. And we are out of candy, OK?"

I was momentarily speechless. It's what happens to me when someone says something cruelly calculated to wound and dismiss. The little kid he spoke to was having a similar response, I noticed. She could hardly have been more than eight or nine.

"She's as American as you are," I finally piped up when I found my voice. The storekeeper, who I know to be the grandson of immigrants, looked at me without speaking. "How can you say that to her?" I asked. "Do you not understand how dismissive it is?"

Apparently he did understand and he was fine with it. I put the milk down on the counter and I left the store. In all the years I have lived in Queens, which is the most ethnically diverse county in the world, I had never seen an exchange like it. I could not believe what I had just seen.

But then it occurred to me that this kind of exchange is becoming increasingly inevitable in the hostile climate being carefully fomented by the GOP's leading presidential candidates. By giving voice to hateful anti-immigrant sentiment they have helped set the stage for a new era of intolerance.

Because when political leaders dehumanize hard-working immigrants, they're not just attacking men and women, they're creating an intolerance that fans out to their children too. Contempt is a blunt instrument after all, it doesn't distinguish between old and young.

According to ICE, the largest investigative agency in the Department of Homeland Security, it costs $12.5k to deport just one person. Deporting 11 million of them would cost $137 billion. Does Donald Trump plan to make America broke again because his immigration policy certainly would?

Trump's plan would empty out every restaurant kitchen in the nation, so it would probably make America hungry again too. That he knows this - I assume he's noticed who's working in his own restaurants - makes his cynicism on the issue all the more repulsive.

Playing to the racism of his core support group may get him the GOP nomination but it will come at the expense of the nation itself. His lunatic immigration "policy" is also undermining the more sensible approaches of some of his campaign rivals, with disastrous results for a reform bill.

The only ray of light to be found in Trump's profoundly socially damaging presidential run is the fact that his candidacy seems to be undermining not only himself but the GOP field around him. Bashing hard-working immigrants to win the support and votes of the people who hate them is just not the American way.

All that anti-immigrant rhetoric eventually filters down to the streets, where the gloves can really come off. And this week, for the first time since I moved to New York, I saw it happen. If it can happen in Queens, it can happen anywhere in the US.

It's time to take Trump and his cohorts to task for it. They’re not making America great, they’re dismantling everything it stands for.