There have been 5.404 million U.S. cases since the start of the pandemic, according to the Center for Systems Science and Engineering at the university.
On Sunday, there were slightly more than 42,000 new cases, the lowest figure in seven weeks. The last time the daily total was lower was June 29, Johns Hopkins figures show. There were fewer than 600 deaths Sunday, ending five straight days with at least 1,000.
With the exception of Friday (64,000), U.S. cases have shown a gradual decline since a one-day peak of 77,000 cases in mid-July.
In California, public schools in Los Angeles announced an "unprecedented" testing and contact tracing program for students and staff on Sunday.
Austin Beutner, superintendent of the the Los Angeles County Unified School District, said it's is partnering with the University California Los Angeles, Stanford University, Johns Hopkins University and Microsoft in the effort, which aims to provide periodic testing to hundreds of thousands of students and employees during the new school year, which begins Tuesday with online classes.
"Extraordinary circumstances call for extraordinary actions, and while this testing and contact tracing effort is unprecedented, it is necessary and appropriate," Beutner said in a statement. "This will provide a public health benefit to the school community, as well as the greater Los Angeles area."
The scale of the program, he said, will allow students to get back to school "sooner and safer" while providing lessons for other U.S. school systems.
Los Angeles County has seen almost 222,000 cases and 5,250 deaths.
In Florida, health officials reported the lowest daily case figure since late June, with fewer than 3,800.
Miami-Dade County, which has seen more cases than any other in Florida, surpassed 2,000 deaths over the weekend. The city's positivity rate fell to 10.3%, the lowest mark in two weeks.
In Texas, Dallas County reported more than 5,300 new cases after clearing a backlog caused by issues with the reporting system. California recently saw similar problems.
The backlog accounted for 5,200 of the new cases, most of which were from July.
"It is expected that there will be more batches of cases missed by the state's system being reported in the coming days," Dallas County Judge Clay Jenkins said. "All this reinforces the importance of self-isolating and following CDC guidance if you were tested and awaiting results."