At a testing site in New Orleans, a line formed at dawn. But city officials ran out of tests five minutes after the doors opened at 8 a.m., and many people had to be turned away.
In Phoenix, where temperatures have topped 100 degrees, residents have waited in sweltering cars for as long as eight hours to get tested.
And in San Antonio and other large cities with mounting caseloads of the virus, officials have reluctantly announced new limits to testing: The demand has grown too great, they say, so only people showing symptoms may now be tested — a return to restrictions that were in place in many parts of the country during earlier days of the virus.