In the USA, a considerable number of states (30 counting 16 years as “adult”) allow the marriage of underage children under certain constraints. And these marriages do happen; whilst proportionally they are a tiny minority, to those victims it is nothing less than state-sanctioned child sex abuse.
In terms of numbers, Unchained at Last (via Wikipedia) found that between 2000-2010 there were 167,000 children in marriages; 13% were boys (I mention boys because most articles start with the girls). But weren’t they all children marrying each other? Only in 14% of cases.
The USA government condones and supports child sex abuse.
The overwhelming majority of not just the rest of the world, but even third-world countries are better on the marriage loophole allowing child sex abuse. Trump: For the victims of those marriages, USA is the “shit-hole”.