Handguns are for sale at a gun shop in Merrimack, N.H., in November 2016. (Dominick Reuter/AFP/Getty Images)

New Hampshire this week passed a law allowing residents to carry a concealed handgun without a permit, joining a growing number of states that are allowing residents to carry weapons out of sight without a license.

At least 11 states have passed laws allowing the concealed carry of guns without a permit, and 16 states have introduced legislation this year to do the same, according to the National Conference of State Legislatures and the National Rifle Association. Gun rights advocates see the laws as the next frontier in Second Amendment rights. But the legislation has been controversial in many places where it has been introduced, with law enforcement members, politicians and gun proponents arguing that the bills go too far.

“That’s kind of the next step in expanding law-abiding gun owners’ constitutional right to self-protection,” said Jennifer Baker, a spokeswoman for the NRA’s Institute for Legislative Action. “It’s where a lot of states are moving.”

Nationwide, the legislation has been contentious and has failed in states that are traditional bastions of gun rights. The legislation has been dubbed “permitless carry” or “constitutional carry,” as proponents believe that people have a constitutional right to carry a gun with as few restrictions as possible. Legislation is pending in states including Kentucky — where gun rights advocates expect it to pass — Texas, Colorado and Indiana.

Idaho, Mississippi and West Virginia passed laws last year that do away with concealed-carry permits, allowing people to carry weapons without them.

In New Hampshire, Gov. Chris Sununu (R) signed a law Wednesday that allows anyone who has purchased a licensed pistol or revolver to carry it, loaded or unloaded, on him or herself or in a vehicle. Sununu’s predecessor, Sen. Maggie Hassan (D), twice vetoed the legislation.

“We have historically allowed people to openly carry a pistol. I don’t see why you have to get a second permit if you’re a law-abiding citizen and legally entitled to own a gun,” Jeb Bradley (R), the majority leader of the state Senate, said in an interview. Bradley and Sununu also said the law puts New Hampshire on equal footing with neighboring Vermont and Maine, which also do not require permits for the concealed carry of handguns.

The legislation went into effect immediately. Previously, gun owners had to apply for a concealed-carry permit with the local police chief, who granted or denied the request. Bradley said that numerous people were unfairly denied permits, but police chiefs testified during hearings that few applications were turned down.

“This bill will eliminate the state’s long-standing permitting system and prevent local law enforcement from making important determinations that help keep guns out of dangerous hands,” Portsmouth Police Commissioner Joseph Plaia said in a statement. He is a member of Granite State Coalition for Common Sense, an offshoot of Americans for Responsible Solutions, a gun control group founded by former congresswoman Gabrielle Giffords.

Shannon Watts, founder of Moms Demand Action for Gun Sense in America, said the passage of such laws are an “anomaly” and occur in “legislatures that have been doing the NRA’s bidding.”

Montana Gov. Steve Bullock (D) vetoed a bill allowing for the carrying of concealed guns without a permit on Thursday. Bullock said in a veto letter that the state’s sheriffs may require safety training before granting a concealed-carry permit and can deny permits to people struggling with mental illness. He equated the bill to allowing people to drive cars, fly planes or erect buildings without determining if they are eligible and able to do so.

“While I will fiercely defend the 2nd Amendment rights of our citizens, I cannot support an absurd concept that threatens the safety of our communities by not providing for the basic fundamentals of gun safety or mental health screening,” Bullock wrote.

South Dakota Gov. Dennis Daugaard (R), who said he is a lifetime member of the NRA, has vowed to veto a bill that would establish permitless carry in the state. South Dakota does not require a permit to purchase a gun and a concealed-carry permit costs $10 and requires a background check. In an op-ed in the Rapid City Journal, Daugaard wrote that he would not sign “bad legislation” that could have many unintended consequences.

In Missouri, lawmakers last year overrode Gov. Jay Nixon’s (D) veto and passed a package of gun legislation that established a “stand your ground” law and allowed people to carry concealed handguns without a permit.

“The basis of this whole bill is that it allows law-abiding citizens to protect themselves and their families,” state Sen. Brian Munzlinger (R), the bill’s sponsor, said at the time. His office declined to comment on Thursday. Concealed-carry permits were no longer necessary in the state starting Jan. 1.

The legislation sparked an outcry, with many concerned that it could put residents at risk and some public safety officials, including St. Louis Mayor Francis Slay (D), and the city’s police chief, Sam Dotson, said it would make neighborhoods less safe and make it more difficult for police to do their jobs.

Correction: An earlier version of this article incorrectly listed Missouri Gov. Jay Nixon’s political affiliation. He is a Democrat. The article has been updated.