But experts see evidence of a second wave building in Arizona, Texas, Florida and California. Arizona “sticks out like a sore thumb in terms of a major problem,” said Jeffrey Morris, director of the division of biostatistics at University of Pennsylvania’s Perelman School of Medicine.

Arizona’s daily tally of new cases has abruptly spiked in the last two weeks, hitting an all-time high of 1,187 on June 2.

This week, its Department of Health Services sent hospitals a letter urging them to activate emergency plans and prepare to staff beds. The department’s director, Cara Christ, told a Phoenix television station that she was concerned about the rising case count and percentage of people tested who are found to be positive. The state, she said, has no current plans to shut down businesses a second time, but she didn’t rule it out.

“That’s not part of our discussion -- that’s not on the table for what we’re looking at -- but we know that we have a whole range of options,” she said in an interview Tuesday with Fox 10 news.

Mobile Texans
In Texas, Governor Greg Abbott was criticized for an aggressive reopening last month. Mobile-phone data show activity by residents is rebounding toward pre-Covid levels, according to Morris’s collaborators at the Children’s Hospital of Philadelphia’s PolicyLab.

That could reflect a perception that the virus wasn’t “ever a big threat,” said Morris, who recently moved to Philadelphia after 20 years in Houston. Brazoria County, near Galveston on the Gulf Coast, has seen just a 6% reduction in visits to nonessential businesses, compared with a roughly 50% reduction in New York City and Los Angeles County, according to the PolicyLab.

Bucking the trend is Georgia, which was the first U.S. state to reopen. Covid cases there have plateaued.

Despite some local outbreaks, “their sea levels did not rise,” said David Rubin, director of the PolicyLab, which has been modeling the virus’s spread in local areas around the country. “They’ve kind of held this fragile equilibrium.”

Creeping In
California was the first state to shut down its economy over the coronavirus, after one of the nation’s earliest outbreaks in the San Francisco Bay Area. It has been slower than most to reopen.

Even so, the state has also seen the number of people hospitalized with Covid-19 rebound in the past two weeks, as more commerce picks up. Case counts are climbing too, although state officials attribute that more to increased testing and say it’s a sign of their preparation.