This is the newly updated map of COVID-19 cases in the United States, updated, presumably, because of the new emphasis upon testing:
How do we know this is the recent of recent testing? Look at the map of active cases:
To the degree numbers of active cases fall down on top of cumulative cases means these are recent detections.
In other words, while concerns about importing COVID-19 cases from Europe are of some concern, the virus is here, the disease is here, and a typical person in the United States is much more likely to contract the disease from a fellow infected American who has not travelled than a European person (note there are no prohibitions against Americans coming home) coming here.
The lesson is that if a process has a certain rate of growth, and the sampling density in time isn’t keeping up with that growth, it is inevitable there will be extreme underreporting.
I would like to understand if that suppression of testing was deliberate or not. Between the present administration’s classifications of COVID-19-related information under National Security acts and the documented suppression of information on federal Web sites relating to climate change, I would be highly suspicious that such suppression, which would put 45 in an unpopular light, was accidental.
(update, 2020-03-15, 2113 EDT)
In the above, note that once a sampling density in time is increased to match growth of the counts, then it will appear as if the rate of growth of cases is extraordinary. That is false, of course, but it is a consequence of the failure to have an adequate sampling density (in time) in the first case.
(update, 2020-03-20, 1632 EDT)