CONCORD, N.H. — New Hampshire has decriminalized the possession of small amounts of marijuana, joining more than 20 states including all of New England in easing criminal penalties on pot.

Republican Gov. Chris Sununu on Tuesday signed the bill that reduces the penalty for possession of up to three-quarters of an ounce of marijuana and a much smaller amount — 5 grams — of hashish from a criminal misdemeanor to a civil violation. The legislation takes effect in 60 days.

Under the new law, a violation would be punishable by a $100 fine for a first or second offense and by a fine of up to $300 for any subsequent offense within three years. A person could be charged with a misdemeanor, if they are found with marijuana for a fourth time within the three years.

Minors caught with either would be subject to a delinquency petition. In addition, police cannot arrest someone for a marijuana violation, and any money collected from the fines will go toward alcohol and drug abuse prevention and treatment.

“The governor deserves credit for his steadfast support of this commonsense reform,” Matt Simon, New England political director for the Marijuana Policy Project, said in a statement. “Unlike his predecessors, who opposed similar proposals, Gov. Sununu appears to understand that ‘Live Free or Die’ is more than just a motto on a license plate.”

Supporters argued the change would ensure young people’s lives aren’t ruined by getting caught with marijuana. They also said it would allow law enforcement officers to focus resources on serious crimes.

Opponents said decriminalization sends the wrong message as the state battles a drug crisis.

The House originally approved changing possession of up to an ounce of marijuana from a misdemeanor to a violation. The Senate reduced the amount to three-quarters, and the House agreed.

The bill signing comes weeks after Vermont Gov. Phil Scott, a Republican, vetoed a measure that would have legalized marijuana in that state. Vermont House Republicans then blocked consideration of the marijuana bill during a veto session, prompting Scott to appoint a commission to study the issue.

Maine and Massachusetts’ voters approved legalization in ballot measures last year.