Sometimes the most important economic events announce themselves with huge front-page headlines, stock market collapses and frantic intervention by government officials.
Other times, a hard-to-explain confluence of forces has enormous economic implications, yet comes and goes without most people even being aware of it.
In 2015 and 2016, the United States experienced the second type of event.
There was a sharp slowdown in business investment, caused by an interrelated weakening in emerging markets, a drop in the price of oil and other commodities, and a run-up in the value of the dollar.
The pain was confined mostly to the energy and agricultural sectors and to the portions of the manufacturing economy that supply them with equipment. Overall economic growth slowed but remained in positive territory.
The national unemployment rate kept falling.
Anyone who didn’t work in energy, agriculture or manufacturing could be forgiven for not noticing it at all. Yet understanding this slump — think of it as a mini-recession — is important in many ways. It helps explains the economic growth spurt of the last two years.
The end of the mini-recession in the spring of 2016 created a capital spending rebound that began in mid-2016, and it has contributed to speedier growth since. Oil prices have reached four-year highs, a major factor in a surge in business investment this year.
It helps explain some of the economic discontent evident in manufacturing-heavy areas during the 2016 elections. It offers warnings for where the next downturn might come from, and shows how important it is for policymakers to remain watchful and flexible about unpredictable shifts in the global economy.
Most important, the mini-recession of 2015-16 offers a cautionary tale for any policymaker who might want to think of the United States as an economic island.
The episode is stark evidence of the risk the Trump administration faces in threatening economic damage to negotiate leverage with other nations on trade and security.
What happens overseas can return to American shores faster and more powerfully than once seemed possible.