New York state has joined California in telling its residents to stay at home during the coronavirus pandemic, putting nearly 60 million on lockdown.
Earlier, California's state governor Gavin Newsom issued a state-wide "stay at home" order, which took effect from Thursday evening and will remain in place until further notice.
He said the state needed to "recognise the reality" and "make tough decisions", although conceded that home isolation was not his "preferred choice".
New York governor Andrew Cuomo also issued an executive order to state residents, meaning all non-essential workers must stay at home or cease working completely.
Mr Cuomo added that over-70s, or those with underlying health conditions, must stay at home, save for solo exercising.
Speaking to the people of New York, he pleaded with them to listen, saying: "Your actions can affect my health, that is where we are."
The new restrictions will be enforced with fines and forced closure of businesses should they flout the rules.
The states of New York and California have been some of the hardest hit in the US, with combined confirmed cases of COVID-19 at more than 6,500, with 57 people having lost their lives.
California's governor said modelling has shown 56% of California residents are expected to contract COVID-19 over the next eight weeks, requiring nearly 20,000 more hospital beds than the state can currently provide.
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He also warned infection rates are doubling every four days in some parts of the state.
Los Angeles, the nation's second-largest city, is likely to be "disproportionately impacted" in the coming weeks, Mr Newsom added.
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