America’s gross national debt is $36trn, or $107,000 per person. It is rising fast and will probably soon be rising even faster. If Donald Trump’s election campaign was anything to go by, his return to the White House heralds a flurry of tax cuts on everything from corporate profits to tips. In the fiscal year that ended in September, Uncle Sam spent $1.8trn more than he collected in taxes (6.4% of GDP, or over double the annual earnings of America’s seven biggest firms). By one estimate, Mr Trump’s agenda could raise borrowing by $4.1trn in the coming decade.