SEATTLE (AP) — An increase in testing for the coronavirus began shedding light Monday on how the illness has spread in the United States, including among nursing home residents in one Washington state facility.

New diagnoses in several states pushed the tally of COVID-19 cases past 100, and New Hampshire reported its first case, raising the total of affected states to 11. Seattle officials announced four more deaths, bringing the total in the U.S. to six.

In Seattle, King County Executive Dow Constantine declared an emergency and said the county was buying a hotel to be used as a hospital for...