By Darrell Dow

Donald Trump’s biggest applause line during the 2016 campaign was his promise to erect a wall along America’s southern border and make Mexico pay for it. Trump did not produce a slew of wonkish policy proposals, but he did provide a simple and workable remittance plan to fulfill his promise: require proof of lawful residence before allowing outgoing wire transfers to Mexico.  Trump reckoned that threatening to restrict remittances would compel Mexico to make a one-time payment of $10 billion to pay for the wall. 

“It’s an easy decision for Mexico,” Trump said in 2016. “Make a one-time payment of $5-10 billion to ensure that $24 billion continues to flow into their country year after year.”

The billions flowing out the U.S. economy into Mexico show just how vital remittances are to the Third World. 

Remittances from the United States are a big chunk of Mexico’s…