New York, New Jersey and four other Northeastern states are forming a working group to keep a close watch on the coronavirus outbreak throughout the region and coordinate plans to reopen parts of the economy as soon as it's safe to do so.

Calling the region the "Covid corridor," the governors said they would carefully weigh the public health risks before allowing companies to resume operations. Commerce throughout the region and much of the U.S. has ground to a halt after states shuttered nonessential businesses and issued orders requiring most residents to stay indoors to slow the pandemic.

"I think this regional compact is premised on the idea that you're not going to have a healthy economy if you have an unhealthy population, so we've got to do both," Pennsylvania Gov. Tom Wolf said on a conference call Monday led by New York Gov. Andrew Cuomo.

The Northeast has been hit particularly hard with the largest outbreak concentrated in New York where there are more coronavirus cases than any other country outside the U.S. There are more than 558,000 cases in the U.S. as of Monday afternoon with more than 300,000 of them concentrated between the six Northeastern states.

Cuomo said each state will name a public health and economic official that will jointly decide when to start easing restrictions designed to curb the Covid-19 outbreak, taking into account both public health and economic concerns.

"State boundaries mean very little to this virus," Cuomo said. "We started this journey together and we're going to end it together."

Connecticut Gov. Ned Lamont cited a resurgence in cases in Hong Kong, Singapore and Japan after those areas appeared to have the outbreak under control and started reopening commerce.

"That would be so demoralizing for our economy," Lamont said.

They were joined by New Jersey Gov. Phil Murphy, Delaware Gov. John Carney and Rhode Island Gov. Gina Raimondo.

Earlier on Monday, at least some of the governors on the call spoke with White House officials, including Vice President Mike Pence and Coronavirus Response Coordinator Dr. Deborah Birx, Murphy said on social media. He added that they discussed the need for rapid and broad testing throughout the U.S.

California Gov. Gavin Newsom, Oregon Gov. Kate Brown and Washington Gov. Jay Inslee later announced a similar regional partnership on the West Coast. Each state will still develop its own plan to reopen the economy, but all three governors agreed to prioritize certain principles, including placing health first and using science to inform policy.

"COVID-19 doesn't follow state or national boundaries," Newsom's office said in a statement. "It will take every level of government, working together, and a full picture of what's happening on the ground."

The Northeastern governors, led by Cuomo, announced the coronavirus group hours after President Donald Trump claimed in a tweet that he, not state leaders, has the power to decide when to "open up" country.

"It is the decision of the President, and for many good reasons," Trump said. Legal experts say Trump is wrong. U.S. law gives state governors wide latitude to protect the health and safety of their constituents. Trump also never declared a nationwide lockdown, so there's no mechanism by which he could order a nationwide reopening now.

The White House instead provided nonbinding guidelines on social distancing, which were recently extended through the end of April, while most states have imposed stringent restrictions on businesses and individuals in an effort to clamp down on the spread of the virus.