Migrants transferred $68.3 billion to the Spanish-speaking world last year—higher than a pre-recession peak of $64.5 billion in 2008. Most of those remittances came from immigrants in the United States sending money back home, according to a new Inter-American Dialogue study set to be released on Tuesday and previewed by The Wall Street Journal.

The study’s authors attributed much of the remittance gain to the increase in Central American immigrants entering the United States. A spike in gang violence has caused a surge in unaccompanied children and families attempting to cross the border: In just October and November in 2015, 10,500 children crossed the border alone, according to The Washington Post.

Remittances back to those violence-ravaged countries, especially Guatemala and Honduras, saw some of the largest increases. The total amount of money transferred to Guatemala jumped 15% last year, and remittances to Honduras jumped by more than 10%, The Journal reported.

Researchers also attributed part of the remittance growth to the depreciation in some South American currencies, incentivizing immigrants to send more money back home.

Financial services provider Western Union, which is one of the leading options for remittances, reported a 3% growth year-over-year in customer transactions, but the company’s reported revenues declined by 2% due to the strong dollar.