Over its half-century in the heart of Portland, Ore., Powell's Books has survived an unending array of foundational threats: the oft-anticipated death of reading, the rise of Amazon, the supposedly irretrievable abandonment of the American downtown.

None of that provided preparation for the tumult of the past two years.

The pandemic shut down its stores for several months and turned downtown into a place best avoided. Black Lives Matter protests drew opportunistic anarchists who brought mayhem, triggering a fierce crackdown from law enforcement. Growing ranks of homeless people erected encampments in front of storefronts blinded by protective sheets of plywood. Forest fires choked the air, pervading a near-biblical sense of doom.

A quirky, old-school enterprise, Powell's has retained its traditional aura in the digital era while standing as a hero in a now-familiar tale of American urban rejuvenation. Its flagship store — a grand warren of books filling out a former car dealership — anchors a once dicey neighborhood whose warehouses have been traded in for glass-fronted condos and furniture boutiques.

But the latest plot twist has foreshadowed a potentially unhappy ending. Like the rest of Portland's urban core — and like downtowns across the United States — Powell's is contending with staggering uncertainty.

"People don't come downtown in the way that they used to pre-pandemic," said Emily Powell, 42, owner and president of Powell's Books, founded by her grandfather in 1971.

As a 6-year-old, she helped her father tend the cash register during the Christmas shopping crush. After college, she went to San Francisco, working at a wedding cake business and then in real estate before returning home to join the family firm. Now she is consumed with how to update Powell's in a city facing grave challenges.

"I don't think, in 10 years, you're going to say, 'Good God, what happened to Portland? It never came back,'" Powell said. "But I don't think it's going to be the same. I think there's going to have to be some creative adaptation that happens, and I'm not really sure what that looks like."

In Portland, the uncertainty is especially poignant given the markers of enduring upheaval. Many downtown businesses remain boarded up, reminders of the chaos surrounding last year's protests in one of America's most segregated cities. Homelessness persists.

None of this attracts customers to downtown businesses.

"A lot of people were intimidated by the protests," said James Louie, whose family has controlled Huber's — a restaurant with elegant mahogany dining rooms — for 70 years. "They are also intimidated by the homeless people, even though they are, for the most part, harmless."

Still, Louie added, "I'm optimistic that eventually downtown is going to make a comeback."

That view is prevalent given Portland's celebrated success in having reinvigorated its downtown once before, bucking the American trend toward suburban sprawl.

The question is whether the pandemic and social ferment combine to undermine all that work or instead catalyze the next revival by forcing city leaders to address the legacies of systemic racism and the dearth of affordable housing.

And Powell's also has grievances with its union, whose members were forced to reapply for their jobs after the shutdown.

Among the people overseeing Powell's, gnawing concerns about downtown coincide with an eagerness to seize an opportunity for reinvention.

When the shutdowns hit, the company turned its focus to online sales, which have traditionally accounted for only about one-fifth of its revenues. Powell's is refashioning a clunky system for managing inventory while updating a website that looks like a memorial for the dial-up internet era.

There are plans for whiskey tasting in the rare books room. A new cafe is being installed in a street-facing corner, standing in for the coffee shop that was shuttered during the lockdown.

"We're replacing the nervous system and the brain of the organization at once," said Powell's CEO, Patrick Bassett. "We're starting to think about what we want to be post-pandemic."