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 5,036,387 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.'
The pandemic shows no sign of slowing, and deaths continue to climb, with more than 1,000 deaths reported each day over the past five days, according to data from Johns Hopkins University's Covid Tracker. Since July 21, there have been only four days the US did not report more than 1,000 deaths.
As of this week, five states account for more than 40% of US infections: California (with the most cases in the country), Florida, Texas, New York and Georgia.
New York, once the country's epicenter, has been surpassed by several states that have seen cases spikes in recent months. On Sunday, the state reported the day prior's positivity rate -- how many people are testing positive compared to how many were tested -- was 0.78%, the lowest one-day positive infection rate since the pandemic began, according to the governor's office.
'Our daily numbers remain low and steady, despite increasing infection rates across the country, and even in our region -- and we had the lowest one-day positive rate since we started,' Gov. Andrew Cuomo said in a statement Sunday. 'That's an incredible achievement, all thanks to the hard work of New Yorkers.'
Florida reported 6,190 new cases on Sunday -- the 13th consecutive day the state reported more than 6,000 cases, according to CNN's tally. There are more than 527,000 cases among residents in the state, according to the state Department of Health.
California, reporting more than 7,000 cases Saturday for a total of more than 545,000, had a positivity rate of about 6% over the past two weeks, according to health officials. Hospitalizations across the state are dropping, and there are about 5,746 hospitalized patients -- down more than 1,000 from two weeks ago.
In Texas, the governor extended his disaster declaration as the state reported its highest seven-day positivity rate: 19.41%. The previous high, 17.43%, was recorded around mid-July. More than 481,000 infections have been reported statewide and about 7,872 people remain in hospitals.
Schools begin welcoming students back
As schools reopen for classes, researchers are still working to understand the spread and effects of the virus when it comes to children.
Research has shown older children can transmit coronavirus just like adults, and another study said children younger than 5 have a higher viral load from the virus in their noses compared to older children and adults, also raising questions about how likely they are to transmit the virus.
While some US officials have said an infection poses less risks to younger populations, a 7-year-old boy with no underlying health conditions died in Georgia last week, becoming the youngest victim in the state. Earlier this month, two teenagers died in Florida from coronavirus complications, bringing the state's total number of minors who have died in relation to the virus to seven.
With a positivity rate of less than 1%, New York has cleared all school districts across the state to reopen, Cuomo said Friday, adding that plans may change if infection rates begin spiking again ahead of the scheduled reopenings.
Local school districts will decide what their reopenings will look like, whether they choose to return in-person, conduct remote learning or opt for a hybrid model.
The New York City Department of Education will offer a blend of in-person and remote learning options. Families also have the choice of doing all-remote learning.
Department of Education Chancellor Richard Carranza told CNN last week that schools will implement a number of precautions, like requiring face masks, randomized temperature checks and one-way hallways.
Officials will be 'looking like hawks at the numbers,' Carranza said. 'If the numbers of the positivity rate start inching upwards and if it gets to 3%, we will remote learn for the entire system.'
In Georgia, many schools have already reopened.
Just outside Atlanta at North Paulding High School, which suspended then 'rescinded' the suspension of a student who posted a photo of its crowded hallways, six students and three staffers have contracted the virus, according to a letter the principal sent to parents. As a result, the school district said Sunday that the school would have only online learning Monday and Tuesday.
At least 260 students and eight teachers in the Cherokee County School District were quarantined after multiple students and teachers tested positive for the virus during the first week of school. In a statement on its website, the district, which is north of Atlanta, reported positive cases in at least 11 students and two staff members. Among them was a second grader who tested positive for the virus after the first day of school.
Northeast of Atlanta, Barrow County Schools announced the district would start the year virtually after more than 90 staff members were forced to quarantine because they had a confirmed or suspected case of the virus, or were exposed to someone who did.
Thousands gather in small South Dakota city
As the virus runs rampant through many US communities, visitors have poured into a South Dakota city for the 80th annual Sturgis Motorcycle Rally.
The event, hosted in the city of about 7,000, brings in hundreds of thousands of people each year. While officials say this year will be a scaled-back version, people are still expected from all over the country -- including hotspots such as Florida, Texas and Arizona.
In nearby campgrounds, there will be concerts, races and contests every day. City officials say they have recommended social distancing guidelines and capacity limits for bars and restaurants, but none of that is legally enforceable, City Manager Daniel Ainslie told CNN.
'I guarantee you, any number of people brought the virus to this event and it will spread among many of the participants and will be taken back to their homes where they will spread it further,' Dr. Schaffner from Vanderbilt University told CNN on Sunday. 'This is an accelerant of the outbreak that we're having in the United States today.'
South Dakota has so far recorded one of the lowest number of cases with about 9,605 infections, according to Johns Hopkins data.
Dr. Carlos del Rio, an infectious disease professor at Emory University, isn't worried about the rally itself because it will mostly be outside, he said. Instead, he said he fears what will happen after hours, when people go to restaurants, bars and begin congregating indoors.
'I'm quite concerned that this event could potentially be a disaster,' he said. 'There could not only be a lot of transmission there, but a lot of people could get infected there and go back to their home states and take the virus over there.'
The event is scheduled to run through August 16.