More than 20 million people in the US may already have been infected with Covid-19, according to the latest estimate by health officials.
The Centers for Disease Control (CDC) says the true number of cases is likely to be 10 times higher than the reported figure.
It comes as the state of Texas halted its reopening as infections and hospitalisations surged.
The US has recorded 2.4m confirmed infections and 122,370 deaths.
Some southern and western states have been reporting record numbers of cases in recent days.
The University of Washington predicts 180,000 US deaths by October – or 146,000 if 95% of Americans wear masks.
“Our best estimate right now is that for every case that was reported, there actually were 10 other infections,” CDC Director Dr Robert Redfield told reporters.
This was because testing was restricted to people with symptoms and asymptomatic carriers were not tested, he said. “We probably recognized about 10% of the outbreak by the methods that we use to diagnosis between the March, April and May,” he said.