New York, New Jersey and Connecticut have asked people travelling from states where Covid-19 cases are rising to go into self-isolation for 14 days.
New Jersey’s Phil Murphy said people in the three states had been “through hell and back” and did not want “another round” of virus infections.
Some southern and western states have been reporting record numbers of cases.
The University of Washington predicts 180,000 US deaths by October – or 146,000 if 95% of Americans wear masks.
So far, the US has recorded more than 2.3 million cases of the virus and more than 121,000 deaths.
On Tuesday America’s top infectious disease expert Dr Anthony Fauci told lawmakers there was “a disturbing surge of infection” and “increased community spread” in many southern and western states.