Here are all the known coronavirus cases in the U.S. (There are probably more.)

(Jon Chol Jin | AP file photo) In this Feb. 26, 2020, file photo, members from an emergency anti-epidemic headquarters in Mangyongdae District, disinfect a tramcar of Songsan Tram Station to prevent new coronavirus infection in Pyongyang, North Korea.

Chicago • The number of known coronavirus cases in the United States spiked over the weekend and into Monday, with dozens of new diagnoses bringing the total of confirmations to more than 100.

Public health officials reported that the virus was spreading among people with no history of overseas travel. Schools closed. Governors declared states of emergency.

The New York Times has been tracking every case in the United States for more than a month and maintaining a database using information from federal, state and local officials to keep an accurate count.

The number of patients treated in the United States remains a small fraction of those diagnosed overseas, where thousands of people have died and tens of thousands have been infected. Most states have not had any confirmed cases.

[Read more: Complete coverage of the coronavirus]

But as concern about a broader outbreak spreads, here is what is known about the current cases.

There’s unexplained spread on the West Coast.

For weeks, nearly all the coronavirus cases in the United States could be directly connected to overseas travel or to close personal contact with someone who had recently returned from a trip. In recent days, that has started to change.

Health officials in California, Oregon and Washington state have all reported incidents of the virus turning up in people with no high-risk travel history, suggesting that it could be spreading undetected within the United States.

The toll has been especially severe at a nursing home in suburban Seattle.

Six people have died in Washington state.

The first coronavirus deaths in the United States were reported over the weekend in King County, Washington, which includes Seattle.

The first fatality, announced Saturday, was a man in his 50s with underlying health conditions. The second, announced Sunday, was a man in his 70s who was a resident of the nursing home in Kirkland, Washington, where several cases have been identified.

On Monday, officials in Washington announced that four more people, including three nursing home residents had died from the coronavirus. Other residents of that facility were hospitalized in critical condition.

Patients have been treated in 15 states.

While coronavirus has been diagnosed on both coasts and in the Midwest, it has mostly been concentrated in just a handful of states.

Combined, California and Washington account for 60 of the cases. Those patients include a mix of people who contracted the illness locally, traveled in China or were passengers on the Diamond Princess cruise ship, which docked in Japan after an outbreak on board. Doctors in Nebraska, where there is a hospital unit specializing in biocontainment, have treated 13 coronavirus patients, all of them former Diamond Princess passengers.

Health officials in Illinois, Florida, Georgia, Oregon, Massachusetts and Rhode Island have all reported multiple cases of coronavirus. And individual patients, all of whom had a high-risk travel history, have been treated in Arizona, New Hampshire, New York, Utah and Wisconsin.

Nearly half of U.S. patients were on the Diamond Princess cruise ship.

Forty-three Americans who spent time aboard the ship, where the virus spread among passengers and crew members, were evacuated and treated in the United States.

Those patients, who were flown out of Japan on two U.S. government flights, have received care at hospitals in California, Nebraska, Texas, Utah and Washington state.

Dr. Matt Willis, the public health officer in Marin County, California, said one Diamond Princess passenger who tested positive was being monitored at a hospital there. The patient, Willis said, was “not sick at all” and eager to return home.

“We’re just sort of waiting to see what plays out as the body fights the virus,” Willis said. “And potentially it could be weeks. And that’s tying up a precious hospital bed for a long time.”

The vast majority of patients traveled overseas.

Though more and more unexplained cases have been identified, most people with coronavirus in the United States recently spent time in a country with a larger outbreak.

A woman in Washington state who traveled to South Korea was diagnosed late last week. On Sunday, the first diagnosis in New York was announced, involving a woman who had traveled in Iran.

And over the weekend, health officials in Rhode Island said two people, including a teenager, who had returned from a school trip to Italy were diagnosed with coronavirus. Others who went on that trip were being held out of class, and the school was closed for deep cleaning.

Several patients have already recovered.

Many people with coronavirus experience only minor symptoms, and some of the first patients in the United States have already recovered and returned to daily life. Those people include a man in Washington state, two people from China who were diagnosed while traveling in California, and a married couple in the Chicago area.

“They have now had multiple rounds of negative testing for the virus and are clinically well,” Dr. Allison Arwady, the county public health commissioner in Chicago, said last month as the couple was released from isolation. “They do not need to wear masks, and neither does anyone interacting with them. They have been cleared.”