One generation has dominated American politics for over 30 years

Yet Mr Obama’s tenure turned out to be not a break with the past, but merely a brief respite from it. The two subsequent presidents, Donald Trump and Joe Biden, were both also born in the 1940s. And since they are the two main candidates in this year’s election (at least for now), one of them is likely to be president for another four years. Even if Mr Biden withdraws his candidacy, Mr Trump is currently the favourite anyway. That means their generation could end up locking up the presidency for most of the period from 1993 to 2029—getting on for 40 years.