California has declared a state of emergency after announcing its first coronavirus death, bringing the US death toll from the disease to 11.
The 71-year-old man, who died in a hospital near Sacramento, had underlying health conditions and had been on a cruise ship, said officials.
The White House moved on Wednesday to expand testing nationwide for the disease.
There are now at least 150 reported US patients with Covid-19 in 16 states.
Worldwide, authorities have confirmed more than 92,000 cases of the virus, of which more than 80,000 are in China. More than 3,000 people have died globally, the huge majority in China.
Ten of the 11 US deaths were in Washington state, but the outbreak has also flared up in Texas and Nebraska.
Meanwhile Washington and Florida both declared states of emergency over the weekend to help prevent the coronavirus.