When the California Labor Commissioner’s Office ruled last month that an Uber driver was an employee deserving of a variety of workplace protections — and was not, as the company maintained, an independent contractor — it highlighted the divided feelings many Americans have about what is increasingly being called the “gig economy.”

On one hand, start-ups like Uber, which is appealing the decision, and Lyft make it possible to conjure up rides on a smartphone in a few seconds’ time.

On the other, Uber — which directly employs fewer than 4,000 of the more than 160,000 people in the United States who depend on it for at least part of their livelihood — and similar companies pose a challenge to longstanding notions of what it means to hold a job.

As it happens, though, Uber is not so much a labor-market innovation as the culmination of a generation-long trend. Even before the founding of the company in 2009, the United States economy was rapidly becoming an Uber economy writ large, with tens of millions of Americans involved in some form of freelancing, contracting, temping or outsourcing.