On this date in the year 1848, in the conquered and occupied Federal District of Mexico, the Treaty of Guadalupe Hidalgo was signed by representatives of US President James Polk and interim Mexican President Antonio Lopez de Santa Anna, ending the war between the two countries.
By every possible measure, the war ended as a decisive victory for the United States and a humiliating defeat for Mexico. As a result of the treaty, Mexico ceded all rights to territory north of the Rio Grande and the Gila River, including all of California, Nevada, Utah, and Texas, parts of Kansas, Colorado, Wyoming, and Oklahoma, as well as the parts of Arizona and New Mexico not later bought in the Gadsden Purchase. From Mexico's perspective, a perspective that recognized neither the revolutions in Texas and California nor the Annexation of Texas, the country lost over half of its prewar territory.
The combined Gross State Products of CA, NV, UT, and TX in 2008 were, according to Wikipedia, approximately $3.27 trillion, as Texas and California were our two most productive states. The entirety of Mexico that year produced about $1.55 trillion, less than half of the Mexican Cession's total output even when we exclude the partial states given up in the treaty.
Yes, it's clear that the war was a terrible disaster for Mexico, a loss that to this date grates and shames their national ego, which is why we see the Reconquista movement today, as groups like La Raza weep at the contrast of the prosperity of northern Mexico-in-America versus the failure of southern Mexico-in-Mexico. After all, the land ceded to us was mostly empty. It was southern Mexico that had all the people. We built what we have today from next to nothing.
It's no wonder that, as the US tried to negotiate a settlement with Mexico, many of Mexico's elites asked the US simply to annex the entire country. Even then, the writing was on the wall about the fates of the two nations. And of course to this day Mexicans who long for prosperity and freedom come here, in such great numbers that we're having trouble dealing with it.
In looking back at what has happened since the Treaty of Guadalupe Hidalgo, it becomes clear that our Constitution, our values, and our way of life that are critical to our prosperity we have enjoyed, even as petro-rich Mexico has lagged far behind.