The governors of Pennsylvania, New Jersey, Connecticut, and New York met Thursday for a summit to discuss coordinating marijuana policies.

“It is complicated, it is controversial, and it is consequential,” said New York Gov. Andrew Cuomo, who hosted the Regional Cannabis Regulation and Vaping Summit. “If you don’t do it right you can do harm, and the whole purpose here is to do good.”

Governors of the four states, all Democrats, support legalizing cannabis for adult recreational use. Pennsylvania’s Tom Wolf expressed his support for the first time in late September, saying that most of the Keystone State’s residents back it and that the state has a wealth of knowledge from the experiences of other states to guide it. New Jersey’s Phil Murphy ran on a platform to legalize it.

“It’s imperative that we focus on bringing the conversation about cannabis into the open and making sure there is proper regulation,” said Wolf. “When we establish a marketplace for cannabis, social justice and empowerment initiatives must be considered.”

Wolf said the summit resulted in “meaningful agreements” on market regulation, public health, law enforcement, and vaping best practices.

Cuomo, in a statement, said the states agreed to a series of principles that set a cannabis tax structure, best practices for safety and contamination, and restrictions on advertising.

Banking was a key issue under discussion, said Pennsylvania Lt. Gov. John Fetterman, who also attended. Officials from Colorado and Massachusetts, where marijuana is legal for recreational use, provided guidance, he said.

“Until the federal government reconsiders marijuana as a Schedule 1 substance [along with heroin or LSD], businesses have to deal in all-cash,” Fetterman said. “It’s a real impediment. The states have to explore options because they weren’t getting leadership or guidance from the feds.”

Connecticut Gov. Ned Lamont said the “patchwork quilt of marijuana regulations makes no sense at all.”

Lamont said the group came up with “very preliminary” principles concerning how to regulate recreational marijuana, agreeing to have similar policies for THC content, and edibles, in addition to dissuading people from turning to the illicit market.

Fetterman underlined the last point.

“Legalization is the pathway to regulation,” he said. "And regulation produces the desired outcome that everybody wants. We want to suffocate the black market, take it out of the shadows, test purity to make it safer, and produce revenue.

“Regionalization creates challenges but also creates opportunities," Fetterman continued. "What we had was an important conversation to get us all thinking about it on the same page.”

Associated Press contributed to this story.