Microsoft, based in the Seattle suburb of Redmond, on March 4 asked employees to work from home. Shortly after, Amazon did the same for its Seattle-area office workers. Washington public schools have been closed since March 16, and some private ones shut a week before that.

That said, Washington implemented a formal stay-at-home order only last week and the virus spread among workers at some companies that remained open. As of last weekend, 54 Boeing workers in the Puget Sound were sick.

In Oregon, where Governor Kate Brown declared an emergency March 8 and canceled school March 16, the rate of increase has been relatively flat. In the 10 days since Oregon topped 100 confirmed patients, cases have risen to 606. At the same point in its outbreak, Florida had triple that, New York more than quadruple and Michigan more than 7½ times, according to data compiled by the University of Chicago.

There’s further evidence for the efficacy of distance measures in Ohio, where Mike DeWine was among the first U.S. governors to close schools, bars and restaurants. He even supported closing the polls for the state’s March 17 primary after a court refused to.

Before Ohio had reported its first confirmed case, DeWine announced March 3 that Ohio would bar general spectators at the Arnold Sports Festival with Arnold Schwarzenegger in Columbus, an event that draws thousands from many countries. DeWine said he agonized, but now the decision seems like “a no-brainer.”

State officials caution that the virus likely is more widespread than reporting suggests because of limited testing -- and that Ohio could see as many as 10,000 new cases a day at the peak of the outbreak. But the state had 1,933 and 39 deaths as of Monday, fewer than neighboring Pennsylvania and Michigan.

Detroit, with a large population of poor citizens, has been a particularly hot zone. New Orleans, Chicago and Phoenix all are predicted to be especially virulent as well. And even within states that acted early, similarly afflicted areas may still emerge.

One example is California, the nation’s most populous state, with its diverse populations and geographies. Providence’s Hochman, who operates hospitals in northern California, Los Angeles and suburban Orange County, says it’s “six different states rolled into one.”

Even just within Los Angeles, downtown may face case intensity similar to New York City’s because of its density, he said. There’s not enough data to be sure.

San Francisco’s top public health official, Grant Colfax, said it’s too soon to know whether early and aggressive social distancing orders made a difference. “I certainly am hoping and praying that that is the case,” he said.