Child marriage sounds like a problem from another time, another place.
An advocate against it calls it an American problem right now.
"More and more legislators are reaching out and saying 'How can I help?'" said Fraidy Reiss, the founder of Unchained at Last. Her organization advocates against forced and child marriage nationwide.
Colorado data shows there were almost 5,000 kids - boys and girls - under 18 years old, who were married between 2000 and 2015. The majority were teen girls, and most often married men 18 years or older. In some cases, girls as young as 17 years old married men who were 31 years old.
In other cases, girls as young as 15 years old married men who were 25 years old. About once a year a girl under 15 years old got married. All of these numbers remain faceless for now. State data doesn't give any clues about who is entering these relationships or why.
"Children can be easily forced into a marriage or forced to stay in a marriage," said Reiss.
"Regardless of whether the kid wants to or not there's some coercive element there because the kid can't really make that kind of a decision on his or her own," said 9NEWS psychological expert Dr. Max Wachtel.
He said the damaging effects of some underage marriages can last a lifetime.
"Honestly, one of the biggest unintended impacts for kids getting married to each other or getting married to somebody who is older is maybe pushing the kid into sexual activity before he or she is ready for it," Wachtel said.
He added that kids who want to get out of those marriages have few ways to leave.
"Because of that feeling of being trapped, a lot of anxiety, a lot of depression can come up," Wachtel said.
There is no minimum age for a ceremonial marriage in Colorado.
The law on the books allows someone under 18 to petition for marriage.
Kids as young as 16 years old, need either parents or guardians to consent, or a judge alone can approve it.
Anyone 15 years old or younger needs parents or guardians and a judge to say it's okay.
What's most perplexing: the minimum age for common law marriage is 18 years old -a law that went into effect in 2006.
Reiss worries that with no minimum age, there's no safety net to catch boys and girls before they fall into dangerous relationships.