The Counter writes: 

“Mexico is now the United States’ single largest agricultural trading partner, largely the result of the North American Free Trade Agreement (NAFTA), a treaty enacted in 1994 that eliminated tariffs on the majority of goods produced and traded between the United States, Mexico, and Canada. Although NAFTA was heralded by the U.S. government for reducing barriers to trade, the pact devastated rural economies in Mexico, flooding the market with cheap, government-subsidized U.S. corn and gutting domestic corn prices by nearly 70 percent. This shift led an estimated 2 million farmworkers to abandon the countryside to seek work in big cities or across the border in the United States.” 

Read more: Mexico is Phasing Out Imports of Glyphosate and GMO Corn. Supporters Say That Could Reverse Years of Damage from U.S. Trade Policy.