Timing. In the history of startups, nothing does more to divine good or bad fortune than the moment an entrepreneur touches down in the market on the wings of a new idea. Nicola Tesla was disastrously premature with his brilliant idea for distributing electricity via alternating current. A century later, Elon Musk's Tesla Motors nearly died before the EV market sparked to life. Last year's No. 1 Inc. 5000 company, OneTrust--which helps businesses comply with new consumer privacy laws--showed what kind of magic can happen when an idea and the need for it glide into the market in total synchronicity.

A rare event such as Covid-19 only underscores how determinative timing can be. If you carefully planned the opening of a restaurant, store, hotel, or cycling studio in 2020, you found that fate was dealing from the bottom of the deck.

Which makes the 2021 Inc. 5000 different from any other in the list's history. Today's fastest-growing privately held American companies proved resilient and flexible during 2020's unprecedented challenges. Among the top 500 companies, the median three-year growth rate soared to 1,819.6 percent, and mean revenue reached $33.4 million. Those companies represent 43,162 jobs.

Some sectors proved more fruitful than others. Computer hardware firms among the top 500, for example, showed median growth of 4,687.8 percent, thanks in part to changes in how people worked.

The fates seemed to go all in for Force of Nature, No. 405 on the list, maker of an electrolyzed water-based virus-killing machine that it devel­oped long before anyone had heard the word Covid. Likewise, Aakash Kumar built Shiftsmart, No. 280, to match gig workers with the employers that fit them best, and when the pandemic scrambled the gig market, Shiftsmart's matchmaking was never more relevant. As that great baseball philosopher Branch Rickey put it, luck is the residue of design.

That's not to say that the 2021 Inc. 5000 companies didn't have to make hard choices. They were not immune to layoffs, belt tightening, or the vagaries of an out-of-whack supply chain. But there's far more certainty and optimism as we look toward 2022--even as vaccination hesitancy stymies efforts to fully reopen, the Delta variant spreads, and Washington gridlock per­sists no matter who's holding power. Consumers are sitting on some $2.5 trillion in excess savings, says Ian Shepherdson, founder and chief economist of Pantheon Macro­economics. And he estimates that at least a third of those dollars will be converted to spending as supply chains get unkinked, employment increases, and pent-up demand gets footloose. "The recovery," he says, "is unstoppable."

Having thrived in last year's social, economic, and political calamity, "unstoppable" might also describe the companies of the 2021 Inc. 5000. As long as they continue to nail their timing.


How the 2021 Inc. 5000 Companies Were Selected

Companies on the 2021 Inc. 5000 are ranked according to percentage revenue growth from 2017 to 2020. To qualify, companies must have been founded and generating revenue by March 31, 2017. They must be U.S.-based, privately held, for-profit, and independent--not subsidiaries or divisions of other companies--as of December 31, 2020. (Since then, some on the list may have gone public or been acquired.) The minimum revenue required for 2017 is $100,000; the minimum for 2020 is $2 million. As always, Inc. reserves the right to decline applicants for subjective reasons. Growth rates used to determine company rankings were calculated to three decimal places. There was one tie on this year's Inc. 5000.