Following the example of Australia and New Zealand, officials in New Brunswick, Canada, said Friday that residents can create a small bubble by picking one other household to interact with. Other provinces in the country are looking to see if the effort is successful.

Regional bubbles — among a group of states, for example — could be a way to get people traveling again and help revive businesses as the world readjusts to life with the coronavirus. The governors of California, Washington, Oregon, Nevada and Colorado have said that they will coordinate the reopening of their states to limit the spread of COVID-19. A travel bubble among those states might make it easier for residents to travel and work across their borders, although spokesmen for the governors of California, Oregon and Washington said that they have not yet discussed creating such a bubble…

“If any states created a bubble to keep out residents of disfavored states, the action would be open to challenge that the bubble violated U.S. constitutional principles of equal treatment,” said Cam Winton, a lawyer with the firm Dorsey & Whitney, who has been advising people dealing with state-imposed coronavirus rules. “Those principles are enshrined in the Privileges and Immunities Clause, the Equal Protection Clause and the so-called Dormant Commerce Clause, which prohibits states from putting undue burdens on interstate commerce.”