Explainer: Why more migrant children are arriving at the U.S.-Mexico border

The number of migrants arriving at the U.S.-Mexico border this year is on pace to be the highest in 20 years, one of U.S. President Joe Biden's top officials said this week, a rise that includes an increase in unaccompanied children.

The Biden administration has struggled to house the growing number of children arriving without a parent or legal guardian, which has left the kids stuck in jail-like border facilities for days. Republicans have blamed Biden for relaxing immigration policies, while some Democrats are concerned about conditions in facilities and why children . . .