Political crisis, economic instability, armed revolt, and the rise of criminal organizations within Mexico pose a significant danger to the Southwest border of the United States. The importance of Mexico to our National Security has been mentioned in policy statements but has been marginalized when contrasted with other more traditional overseas threats. The author seeks to highlight several points of concern such as the changes in the Mexican political process, existing armed insurrection, economic collapses and illegal immigration. These points are viewed in conjunction with a brief overview of the history of Mexico and U.S.-Mexican relations over the last century. The author urges that, because of the proximity of Mexico, its growing economic ties to the U.S., and the increase in the Mexican-American population within the U.S., we must have a better understanding of Mexico in order to prepare appropriate courses of action should Mexico undergo future large scale political or economic upheaval which will have an impact on our National Security.