U.S. pork exports to Mexico have dropped by 11 percent since Mexico announced in August 2010 that it would hit U.S. pork exports with a retaliatory import duty in response to failure of the United States to abide by its commitments made to Mexico in the North American Free Trade Agreement (NAFTA).
The United States shipped $762 million in pork products to Mexico in 2009. Since 1993, the year before the NAFTA was implemented, U.S. pork exports to Mexico have increased by 580 percent.
http://www.nppc.org/News/PressRelease.aspx?DocumentID=26219