The three most populous states set records for new coronavirus cases daily and there are fears of "apocalyptic" surges in major Texas cities if the trend continues.
Coronavirus has killed at least 121,979 people and infected nearly 2.4 million nationwide, according to Johns Hopkins, reports the CNN.
Florida and Texas announced Wednesday that they'd recorded more than 5,000 new Covid-19 cases the prior day, a new daily record.
California reported more than 7,000 cases, obliterating a record hit a day earlier.
In Texas, if the current case trajectory continues, Houston could be the hardest-hit city in the US with numbers rivaling those in Brazil. Infection numbers are also rising in Dallas, Austin and San Antonio, said Dr Peter Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine.
"The big metro areas seem to be rising very quickly and some of the models are on the verge of being apocalyptic," Hotez said.
Models show that Houston could have a four-fold increase in the number of daily cases by July 4, he said, adding that states need to act to stop community transmission.
"That is really worrisome and as those numbers rise, we are seeing commensurate increases in the number of hospitalizations and ICU admissions," he said.
"You get to the point where you overwhelm ICUs and that's when the mortality goes up."
Hotez is also a professor of pediatrics and molecular virology and microbiology, and is working on a potential Covid-19 vaccine.