Children under the age of 18 can be married in every state in the US, but the rules and requirements of doing so vary, making some states more “child marriage-friendly” than others.

In Missouri, children as young as 15 can be married with the consent of just one parent — even if the other parent actively objects to the marriage — and children of any age can be married with a judge’s approval.

According to the Kansas City Star, Missouri’s lax child marriage laws have made it a “destination wedding spot” for 15-year-olds, particularly underage girls that are pregnant by older men.

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Where states like Idaho and Arizona require both parental consent and a judge’s approval for children under 16 to be marry, Missouri requires only a parent’s approval. And unlike in Georgia, parents do not need to swear their approval before a judge, so a pregnant 15-year-old in Missouri can be married to her statutory rapist without ever coming under scrutiny of the law. Children can be married at any age in Missouri — the same is true in 24 other states — but need a judge’s approval if they are younger than 15.

That was the case for several 15-year-old girls married in Missouri in the last 10 years, the Kansas City Star reported, including 14-year-old Heather Strawn who became pregnant after her 24-year-old boyfriend gave her alcohol and had sex with her.

Strawn’s father drove her and her boyfriend 17 hours, from their home state of Idaho, to marry in Missouri so that her child would not be born out of wedlock and her boyfriend would not be arrested for statutory rape.

In several states — including Idaho, Iowa, Maine, New Hampshire, and Vermont — sex with a minor is not considered rape if the people involved are married.

Read more: India Rules Sex With a Child Bride Is Always Rape in a Massive Win for Girls’ Rights

But what happened to Strawn was far from an isolated incident. After reviewing 50,000 marriage licenses, the Kansas City Star found that 15-year-old girls from Utah, Oregon, Colorado, Illinois, and at least 9 other states have flocked to Missouri for underage marriages.

According to Frontline PBS, more than 7,000 children were married in the “Show-Me state” between 2000 and 2014, including some as young as 13. In 2010, the state had one of the top 10 highest marriage rates in the country, Frontline PBS reported, though married children between the ages of 15 and 17 are most common in West Virginia and Texas, according to the Pew Research Center.

Between 2000 and 2010, nearly a quarter million children were married in the US, the non-profit Unchained At Last reported. And while many states have proposed bills that would set the minimum age of marriage at 18, without exceptions, helping to end child marriage, none have succeeded.

A recent effort to pass a child marriage bill in Florida ultimately failed, but resulted in the state raising the minimum age to 17, without exceptions, making it one of the strictest marriage laws in the country.

Read more: This Is What It’s Like to Be a Mom at 10 and Married at 11 in Florida

Around the world, poverty is a major driver of child marriage, according to Girls Not Brides. And child brides are likely to remain in poverty and become vulnerable other forms of abuse and injustice. Married children are often forced to rely on their spouses as they may be too young to do things like drive, open a bank account, or even check into an adult shelter if they are fleeing abuse, the Kansas City Star reported.

“The most important reason we need to end marriage before 18 is because it can so easily be forced,” Fraidy Reiss, founder and executive director of Unchained at Last, told the Kansas City Star. “It is evil to give children the so-called right to enter into this really serious contract before they have the right to safely navigate this contract, to say no to the contract, to be able to get out of the contract. That is evil.”

Global Citizen campaigns in support of gender equality and women’s rights. You can take action here to call on lawmakers to put an end to child marriage and protect women and girls.