Fewer than 200,000 travellers a day have passed through US Transportation Security Administration (TSA) checkpoints since Friday last week.
Daily figures released by TSA show there were more than 2 million passengers a day passing through its checkpoints at the start of the month.
This fell below 1 million on Tuesday March 17, below 500,000 on Sunday March 22, and below 200,000 on Friday March 27.
The US barred entry to any non-US citizens who had been in any of 28 European countries on Monday March 16.
Yesterday 180,002 people passed through TSA checkpoints, down from 2,510,294 on March 29 last year.
Some US states, including Alaska and Hawaii, have introduced mandatory 14-day quarantine periods for all arriving travellers.
TSA currently requires any US citizen arriving from a “coronavirus impacted country” to return through a specially-designated airport, undergo a medical interview and self-quarantine for 14 days.
The Wall Street Journal reports that US airlines are drafting plans for a potential voluntary shutdown of virtually all domestic flights.