According to the latest figures collated by Johns Hopkins University, the US overtook China (81,782 cases) and Italy (80,589).
The grim milestone came as President Donald Trump predicted the nation would get back to work “pretty quickly”, after 3.3 million layoffs.
More than 1,100 people with Covid-19 have died in the US.
At a White House briefing on Thursday afternoon, Mr Trump said: “They have to go back to work, our country has to go back, our country is based on that and I think it’s going to happen pretty quickly.
“We may take sections of our country, we may take large sections of our country that aren’t so seriously affected and we may do it that way.”
He added: “A lot of people misinterpret when I say go back, they’re going to be practising as much as you can social distancing, and washing your hands and not shaking hands and all of the things we talked about.”
As the US overtook China with the most coronavirus cases, Mr Trump cast doubt on the figures coming out of Beijing, telling reporters “you don’t know what the numbers are in China”.
Mr Trump said he would be speaking to President Xi Jinping by phone on Thursday night.
The US president denied that the Chinese leader had asked him to “calm down” the language he uses to refer to the pandemic.
Font: BBC News