On 3 November 2020, a few days after this issue of Futuribles appears, the US presidential election will take place against a background of great communal tensions in the country and an economic crisis relating to the Covid-19 pandemic. As in many developed countries, one of the keys to the electoral outcome lies in the vote of the middle classes. As Julien Damon shows here, their situation has been growing gloomier for several decades now: the gap is growing between the middle classes and the affluent; inequality is increasing; and the reality of upward social mobility is in doubt. This article offers a review of the main American studies of the US middle classes over a dozen years, describing the reality of their development and also, at times, their failure to advance and fulfil their aspirations. He also stresses the risks, in terms of social cohesion, of the emergence of a de facto plutocracy in that country.