WilliamS: In 2015, Mexicans living in the U.S. legally or illegally sent back $24,800,000,000.00 in U.S. currency to Mexico. This overtook Mexico's oil revenue for the first time ever. Trump was eyeballing this as a source of income to build the wall if it doesn't get send back to Mexico. Indirectly, Mexico not getting all this money, could be seems as their money building the wall. I don't know if it is feasible, but I see his point.