Mexico was poor long before NAFTA! This is supported by the fact that as a nation we granted amnesty to somewhere between 12 - 20 million illegal aliens in 1986 (under a Republican President). If Mexico was not "poor" then why were so many of them here? NAFTA did not come along until 10 years later. I note that you gloss right over the trade advantage for Mexican companies into this country. "Some[who?] argue that NAFTA has been positive for Mexico, which has seen its poverty rates fall and real income rise (in the form of lower prices, especially food), even after accounting for the 1994–1995 economic crisis." (^ U.S.-Mexico Corn Trade During the NAFTA Era: New Twists to an Old Story USDA Economic Research Service)
"According to Issac (2005), overall, NAFTA has not caused trade diversion, aside from a few industries such as textiles and apparel, in which rules of origin negotiated in the agreement were specifically designed to make U.S. firms prefer Mexican manufacturers. The World Bank also showed that the combined percentage growth of NAFTA imports was accompanied by an almost similar increase of non-NAFTA exports."
"Maquiladoras (Mexican factories which take in imported raw materials and produce goods for export) have become the landmark of trade in Mexico. Hufbauer's (2005) book shows that income in the maquiladora sector has increased 15.5% since the implementation of NAFTA in 1994. Other sectors now benefit from the free trade agreement, and the share of exports from non-border states has increased in the last five years ... This has allowed for the rapid growth of non-border metropolitan areas, such as Toluca, León and Puebla; all three larger in population than Tijuana, Ciudad Juárez, and Reynosa."
"Production of corn in Mexico has increased since NAFTA's implementation. However, internal corn demand has increased beyond Mexico's sufficiency, and imports have become necessary, far beyond the quotas Mexico had originally negotiated" ( NAFTA, Corn, and Mexico’s Agricultural Trade LiberalizationPDF (152 KB) p. 4)