The US economy is enjoying its longest uninterrupted stretch of expansion since at least 1854, leaping over hurdles including the eurozone crisis, turbulence in the developing world and now trade wars to surpass the 1990s economic boom — at least in duration.

Recessions are typically defined as two consecutive quarters of shrinking gross domestic product, but the National Bureau of Economic Research — the semi-official arbiter of US booms and busts — uses a broader, more qualitative definition, and reckons that the current expansion started in June 2009.

That means that this month the US expansion has now hit its 121st month, making it longer than the golden era enjoyed by the economy from March 1991 to March 2001, and more than twice as long as the average post-WWII expansion.