From CDC website:
CDC is no longer reporting the number of persons under investigation (PUIs) that have been tested, as well as PUIs that have tested negative. Now that states are testing and reporting their own results, CDC’s numbers are not representative of all testing being done nationwide.

The CDC began screening at Los Angeles International, John F. Kennedy International and San Francisco International airports earlier this month as concerns about the new coronavirus began to increase. Last week, the agency began enhanced screening of passengers at two additional airports, Atlanta’s Hartsfield-Jackson and Chicago O’Hare International.

CDC officials said the five airports were chosen because roughly 90 percent of the passengers arriving from Wuhan either on direct or connecting flights flew through them. But efforts to ensure all arriving passengers came through those airports proved difficult. Expanding screening to 15 additional airports where the CDC has quarantine stations in place poses less of a logistical challenge and will enable officials to reach 95 percent of travelers coming from China, officials said.

The screenings, which focus on travelers from Wuhan, involve having them fill out a form detailing their travel and contacts while in Wuhan and whether they are experiencing any symptoms. They also have their temperatures taken.

Here are the 20 airports where travelers will undergo additional screening:

Los Angeles International
John F. Kennedy International
O’Hare International
San Francisco International
Atlanta’s Hartsfield-Jackson
Anchorage Ted Stevens International
Boston Logan International
Dallas-Fort Worth International
Detroit Metropolitan
El Paso International
Honolulu International
Houston George Bush International
Miami International
Minneapolis-St. Paul International
Newark Liberty International
Philadelphia International
Puerto Rico’s San Juan International
San Diego International
Seattle-Tacoma International
Washington Dulles International
In addition to expanding screening, Messonnier said health officials would distribute 350,000 cards to travelers arriving from China with information about the coronavirus and where to call if they think they may have symptoms of the virus. The cards were already being distributed to passengers who arrived at airports that did not have enhanced screening in place.