It has become a truism of the Trump era that the political divisions that have polarised the US electorate have, on a micro-scale, torn families apart. Around Christmas and Thanksgiving, newspapers in the US abounded with advice columns on how to deal with the horror of Trump-voting relatives. We are all supposedly straining to burst our filter bubbles. Less remarked on is the power of Trump to bring families together.

I mention this because my cousin, a left-leaning poet who lives in Chicago and who’s long been at loggerheads with Republicans in our family, has been visiting me in New York this week. She reminded me that unity against a common enemy can have a powerful effect. With Trump in the White House, everyone she knows, including the Republican sibling she had been bickering with about politics for decades, is suddenly and peculiarly on the same side.

Around the dinner table this is surely a good thing; but it strikes me that, in a broader context, it carries significant risks. The left has been invigorated by Trump, but the warping effect of his presidency has the power to push us all rightwards. When we talk about “normalisation” and Trump, we are referring to the scary possibility that his antics may one day cease to appal. There is an even scarier long-range scenario, however, in which what Trump “normalises” are rightwing Republicans who, held up against his standards, suddenly seem the epitome of reasonable.

I find myself actively nostalgic these days for Mitt Romney’s quaint version of crazy – the dog on the car roof, the 14% income tax (but at least we knew what his tax return looked like) – both of which, compared to Trump, seem very mild offences indeed. When Trump goes, the next Republican candidate will merely have to be sane to qualify as an immeasurable improvement.

The magic roundabout

Central Park’s carousel is ‘the best three bucks you can spend in the city if you don’t require caffeine’. Photograph: Sherab / Alamy/Alamy

While my cousin was in town, we took our kids to the carousel in Central Park, the biggest of the carousels run by the New York parks department, and the best three bucks you can spend in the city if you don’t require caffeine. The horses are thunderously huge, the fibre-glass designs on the central cylinder – all gurning clowns and animals twisting to look over their own shoulders in terror – utterly sinister, and the tinkling music oddly transporting.

So many of the cliches of a city disappoint: views from tall buildings get old, skylines grow too familiar to offer much of a thrill, and the reality of the city doesn’t live up to the dream. Thirty-five years later and I’m still not entirely over the day I discovered Swiss Cottage is not, in fact, a Swiss cottage – the theme pub, Ye Olde Swiss Cottage, doesn’t count – but a large roundabout in north London. The Central Park carousel, however, is still a weirdly magical experience, to the extent that two two-year-olds, an 11-year-old and two women in their 40s can go on it and all have a great time.

Irritating ratings

If I could have rated the carousel I would have given it full marks, but thankfully nobody asked. In a department store this week, on the other hand, I was required, before swiping my credit card, to rate my transactional “experience” on a scale of one to five stars. In the coffee shop at the corner of my street it’s the same thing, plus the option to match the rating with a 15% tip – this for buying something over the counter.

The effect of this is not only to slow down what should be a neutral exchange, but to put pressure on the server to inject personality into a situation where none is required. The poor woman in the department store stood grinning apologetically while, wearily, I gave the experience of handing her my credit card five stars.

• Emma Brockes is a Guardian columnist