Researchers at the university's Center for Systems Science and Engineering said there were about 38,200 new cases, a slight increase from the previous day.
New deaths, however, spiked to 1,200 on Tuesday -- a significant rise over about 450 deaths reported the previous two days.
There have been 5.779 million cases in the United States and 178,500 deaths since the start of the pandemic, according to Johns Hopkins.
The American Academy of Pediatrics and the Children's Hospital Association reported Tuesday that there were 74,000 cases among U.S. children over the first two weeks of August -- an increase of 21%. The surge came as schools began to reopen nationwide.
The organizations said severe illness remains "rare among children," but recommended that states "continue to provide detailed reports on COVID-19 cases, testing, hospitalizations, and mortality by age so that the effects of COVID-19 on children's health can be documented and monitored."
The Centers for Disease Control and Prevention said it has changed its testing guidelines, which now say people without symptoms "do not necessarily need a test," even if they've been exposed to the coronavirus.
Last week, the CDC also changed its travel quarantine recommendation to say Americans returning from a trip abroad no longer need to quarantine for 14 days.
In California, Los Angeles County saw a decline in cases Tuesday. Health officials said there were fewer than 1,000 cases for the first time since early June.
Los Angeles County has seen more cases than any other county nationwide.
In Mississippi, hundreds of schools reported new outbreaks Tuesday.
State Health Officer Thomas Dobbs told reporters more than 700 schools saw new cases and urged students to avoid gatherings after a social event was identified as the source of one outbreak in Biloxi.
Hundreds of students were quarantined and in-person classes were closed through Labor Day.
Mississippi has seen the highest number of new cases per 100,000 residents over the past week, according to the Harvard Global Health Institute.