The number means the country holds about a quarter of global cases of the virus and also tops the list with the most reported deaths in the world. Of the country's 5,044,821 estimated cases, 162,851 have been deadly, according to data collected by John Hopkins University.
To put the number in perspective, that means the United States has had more Covid-19 cases than Ireland has people. The number of cases is also slightly higher than the entire population of Alabama.
To put the speed in which the number is growing in perspective: It took the country 99 days to reach 1 million, 43 days to hit 2 million, 28 days for 3 million and 15 days to surpass 4 million on July 23. The number has jumped to 5 million in 17 days.
"This is such a sobering number," said Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University.
"That's a huge number of cases and a very large number of hospitalizations and deaths -- and more to come," Schaffner said. "Because over much of this country, this virus is spreading unimpeded because so many folks are not getting with the program to contain it."