Corporate investment in maquiladoras was expected to produce a Mexican middle class that would become a large market for U.S.goods. But the plan failed to live up to expectations, as skills and productivity lagged behind labor costs and jobs moved to China. U.S./Mexico truck-transport problems also raised costs for Mexican products coming to the U.S. (The middle class may be on the decline in the U.S. as well. Read Losing The Middle Class to learn more.)
To compound the problem, the migration of workers from Mexico City and further south in numbers not easily accommodated in small border towns produced overpopulated slums with high living costs for the Mexican workers. Nonetheless, some argue that the competition between Asia and the U.S. could have become worse without the temporary low-cost labor available to U.S. companies in Mexico.
Because of all these issues, the effects of NAFTA were largely negative for Mexico. The increase in the middle class was insignificant and many of the original NAFTA jobs went to Asia. The concentration of workers at the U.S. border had deleterious effects on the close-knit Mexican family structure because the living conditions in the border towns did not support more than single-worker residence. While some jobs remain in Mexico, the county has yet to realize the full benefits of the agreement.