Mexico backgrounder
Let's take a moment to better understand Mexico. Even though it's right across our southern border, most American's really don't know much about the country. With approximately 106 million residents by UN estimates, Mexico has the 11th largest population, making it more populous than France, Germany, Egypt, Iran, Italy, Israel, or the UK. It has almost four times as many people as Iraq.

Of more import, Mexico has the 12th largest gross domestic product of any country, according to the International Monetary Fund, with an output of about 1.149 trillion dollars a year.

To put that in terms most of our geek readers would understand, Mexico generates revenue of about 70 Googles, given that Google's revenues are about $16.5 billion a year. Curiously enough, if Google were a country, it'd rank 121st in GDP, leaving almost 60 countries with a smaller GDP below it.

Mexico and the United States have somewhat cordial relations. Of course, that wasn't always the case. Courtesy of Manifest Destiny and President James K. Polk, the U.S. back in 1846 thought Mexico would make a nice addition to America. Polk decided to pick a fight with Mexico, essentially instigating the Mexican-American War, and after a lot of tough fighting, pretty much pummeled the other country.

To the victor goes the spoils and Polk got for the U.S. the region that would eventually become California, Nevada, Utah, most of Arizona, and goodly chunks of Wyoming, Colorado, and New Mexico. In return for bringing our troops home from Mexico City, Polk got his chunk of land.

Of course, ain't nothing comes for free, so according to the Treaty of Guadalupe Hidalgo, Articles XII-XV, the U.S. paid the Mexican government $15 million and agreed to assume $3.25 million in debts. Of course, there are now condos in the middle of LA's Century City selling for $15 million, so the U.S. probably got a pretty good deal.

All that took place a decade or so after Sam Houston gave ol' Antonio de Padua María Severino López de Santa Anna y Pérez de Lebrón (who school kids know as Santa Anna) a whoopin', thereby securing Texas' independence from Mexico.

But lest you think all is forgiven or forgotten, Mexican President Carlos Salinas de Gortari brought up the subject in 1994 when discussing the U.S. intervention in Haiti, "Having suffered an external intervention by the United States, in which we lost more than half of our territory, Mexico cannot accept any proposal for intervention by any nation of the region."

Current Mexico
In the intervening 160 years or so, relations with Mexico have characterized by some degree of conflict. According to Mexico: A Country Study, produced in 1996 for the Library of Congress:

In the past, Mexico defied the United States on a number of crucial hemispheric issues. Mexico never broke relations with the Cuban communist regime as did the rest of Latin America in the early 1960s.

Actually, there's some research out of the National Security Archive that now shows Lyndon Johnson was supportive of this in a back-channel way, wanting at least one country friendly to the U.S. to maintain a formal relationship with Cuba.