A few weeks ago, I visited the headquarters of Motorola Mobility in Libertyville, in industrial Illinois. As I sat in an ultra high-tech display room – where the light switches were controlled with a flick of a mobile phone – I asked Sanjay Jha, the CEO, about his industry’s biggest challenges.

The answer took me aback: instead of grumbling about government red tape, cut-price competition from China, or a shortage of bank loans, Jha declared that America has a “counterproductive” approach to immigration. That was not because Jha shares the concerns about migrants that usually hit the headlines: namely, that America is letting in too many. Instead, Jha says that he finds it hard to hire skilled staff because America is denying visas to non-Americans with the skills he needs – including those who have actually studied in America. “We train a lot of our foreign-born students here in the US and then we don’t give them the right to work here. That has made no sense to me at all,” he observed. “It’s becoming increasingly difficult to get the quality of talent that we need to get the job done.”

This is striking – and paradoxical. America, after all, is a country famously founded by immigrants, who considered migration to be not just an economic benefit, but an expression of liberty too. And even today, immigration remains a powerful force. Between 2000 and 2005, some 8 million legal and illegal migrants arrived in the country, the highest proportion in American history. A large proportion of PhD students are immigrants; and a quarter of all tech start-ups between 1995 and 2005 had an immigrant as co-founder.