From the New York Times:

Remittances are among MexicoÂ’s largest sources of foreign currency. Last year, foreign companies invested $23.23 billion to build factories or set up other businesses in Mexico, the second-highest total for foreign direct investment ever. That was still less than the money that the largely low-skilled Mexicans sent home in the form of remittances. (Emphasis mine)

We obviously cannot trust any so-called progress on the part of Mexico's government to stop their people from coming here illegally. Why kill the goose that continues to lay golden (USA dollar) eggs?