The grand General Motors settlement, which emerged after a last-minute strike helped clarify the management’s thinking, may or may not be a turning-point for America’s car industry. But it certainly draws attention to the role that unions still play in the US economy. The plight of the country’s carmakers, a last redoubt of organised labour, hardly makes the case for unionism, you might think. But many American workers see things differently; many politicians too.

The US has an unusually low rate of union membership. Barely 10 per cent of its workers are members (and as few as 7 per cent in the private sector), down from about 35 per cent in the 1950s. Whether you see this as a strength or a weakness most likely depends on whether you think the US economy is succeeding or failing. Weak unions make for flexibility and rapid growth in productivity, the engines of US economic pre-eminence. To see what strong unions do for industrial competitiveness, look at GM. But weak unions also squeeze wages at the bottom, worsen inequality and create economic insecurity, the issues that most preoccupy the country and its politicians.