Coronavirus Live Updates: Fauci Warns U.S. Could Hit 100,000 Daily

As infections surge in the South and the West, the governors of New York, New Jersey and Connecticut — three former hot spots in the Northeast — called on Tuesday for travelers from California and several other states struggling to contain outbreaks to quarantine for 14 days upon reaching their states.

Gov. Andrew M. Cuomo of New York, a Democrat, said that visitors from an additional eight states — California, Georgia, Idaho, Iowa, Louisiana, Mississippi, Nevada and Tennessee — would be required to quarantine for 14 days upon arrival in the state. People traveling to New York from Alabama, Arkansas, Arizona, Florida, North Carolina, South Carolina, Texas and Utah had already been told to quarantine.

New Jersey and Connecticut are advising travelers from the 16 states to quarantine.

It was the latest example of how the shifting geography of the outbreak is once again upending travel regulations. The tristate area’s new restrictions now cover travelers from the nation’s most populous states, and from several of the busiest airports in the country, including those in Atlanta, Los Angeles and Dallas-Fort Worth.

In Massachusetts, which had previously required all visitors to quarantine for 14 days, Gov. Charlie Baker, a Republican, announced on Tuesday that beginning on Wednesday, the state would no longer require travelers from Rhode Island, Connecticut, Vermont, New Hampshire, Maine, New York and New Jersey to do so. “Due to lower infection rates across the Northeast region, our administration is updating our state’s travel guidance,” he said.

Other places are taking different approaches.

Starting July 15, people traveling to Puerto Rico will be required to bring proof of a negative test taken within three days of their arrival, the governor announced Tuesday. Anyone who doesn’t have one will be tested, and those who test positive will have to quarantine for two weeks, and must assume all medical and housing costs.

On Monday, the Department of Defense announced that it had lifted travel restrictions for service members to all but three states: California, Florida and Michigan.