As a conservative Republican, Pennsylvania state Rep. Jesse Topper always leaned toward limited government involvement, no matter the issue.
"When the government is going to intervene, I ask a lot of questions because that's kind of my political ideology," Topper said.
But, like many lawmakers in recent years, when Topper heard from former child brides and advocacy groups that child marriage is a common practice in the U.S. — and in his home state — he said he had to reconsider his political philosophy. He decided to sponsor legislation addressing the problem.
Now Pennsylvania is poised to become the third state, after New Jersey and Delaware, to ban child marriage — with no exceptions. Several states, such as New York, carve out exceptions for court-emancipated minors.
This year, Arkansas, Colorado, Georgia, Louisiana, Nevada, Ohio and Utah have set age limits for marriage, bringing the tally of remaining states with no age limit to wed down to 13. Maine also passed a bill in June setting its age limit at 16; it becomes law on Monday, barring a last-minute veto by the governor.
And in those states that continue to issue licenses to minors, some have improved their review process for doing so to make sure there's no abuse and that the marriage is in the minor's best interest.
Topper's bill passed the state House of Representatives with overwhelming bipartisan support this month and is likely to be approved by the state Senate; Gov. Tom Wolf, a Democrat, has signaled he will sign it.
"I do believe that significant progress continues, and that, in fact, the pace of reforms is picking up across the country," Jeanne Smoot, the senior counsel for public policy and strategy at the Tahirih Justice Center, a nonprofit that advocates for women and girls, told NBC News.
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"I can think of no positive effect on society for allowing children to marry at any age under what we classify as an adult, and that's where I decided to go with the bill," Topper said.
"Marriages for child brides — and most of them are young women, but it could be any children — have an 80 percent failure rate," he added, referring to figures from Unchained at Last, a nonprofit that works to stop child marriage. "What that tells me is it's not something that is 'Prince Charming, happily ever after.'"
A majority of states have minimum marriage ages at 16 or 17. Prior to 2016 — when Virginia became the first state to put its marriage age into law — more than half of the states had no minimum marriage age fixed by statute.
"I think bipartisanship has been a continuing thread as there's common recognition about the problem and concern to address it," Smoot said. "I think one of the things that we noticed over this last year, even six months, has been more leadership by women legislators. ... There have been more survivor-advocates stepping forward over the course of six months to a year to elevate their stories nationally."
Donna Greco, the policy director for the Pennsylvania Coalition Against Rape, said that in conversations with state lawmakers, her group and a coalition of other advocates had to educate elected officials about the links between child marriage and abuse.
"The high school sweethearts they were talking about was the exception, not the norm," she told NBC News. "We really focused on the connection of child marriage with child sexual abuse, with sex trafficking and with ongoing sexual violence within these marriages — our conversation was really helping lawmakers understand that."
In addition to establishing minimum ages to wed, states have also strengthened the review process by which minors are granted marriage licenses, which often require judicial or parental consent. Colorado, for instance, is requiring that a minor to have a guardian appointed to open an investigation and create a report of the circumstances surrounding the marriage petition.
"I think some of the states that have enacted legislation in this interim have put in place really thoughtful measures that have tried to imagine all the ways in which a girl who's being threatened, and intimidated, and coerced, and coached, and doesn't truly want to get married," Smoot said. "And all the ways to the court process needs to be on the lookout to detect and protect her against those threats and not just presuming that one step or one measure or one question at one juncture would be enough."
Despite the progress, some states are lagging behind.
Massachusetts state Rep. Kay Khan, a Democrat, told NBC News that she's been faced with the daunting task of educating skeptical colleagues about her bill to raise the marriage age to 18 with no exceptions.
Last year, she introduced the measure, but it never came to a vote. This year, she re-introduced the legislation and said she is hopeful as the measure has worked its way through the committees of each chamber and has received bipartisan support.
Khan, who chairs the Committee on Children, Families and Persons With Disabilities, credits advocates and survivors who have come forward with helping change opinion in the state about the issue.
"I think part of the problem is convincing people this is a problem because they don't know," she said. "It's about helping our colleagues understand that it is something that is really happening."
Smoot said getting states to set a minimum marriage age is only the first step because the goal is to have age 18 as the marriage age with no exceptions in every state to avoid some states becoming destination spots for child brides.
"It really is a patchwork of provisions around the U.S," Smoot said. "I think that one of the larger concerns that we have is even as we recognize the overall progress is significant from 2016 to now that the patchwork of state laws continues to put all girls at risk of potential forced marriages or other harm through child marriages, given the ease with which they can be taken out of their home state into another state with lax or no laws."
Dartunorro Clark is a political reporter for NBC News.