In the early 19th century, the entirety of what we today call the American Southwest, including all of Texas and California, was part of Mexico.
During that period of time, there was a huge problem of illegal immigration — white American southerners illegally crossing into Mexican territory, particularly Texas, which also had a large indigenous population, and bringing their slave with them. Mexico made a deal with the U.S. to allow limited legal immigration, provided no slaves were brought, and immigrants agreed to abide by Mexican law. This deal was brazenly violated, and whites with slaves continued to pour illegally into Mexico and began setting up cotton plantations. Mexico resisted.
Things came to head in the mid-1840s, when President James K. Polk launched an illegal invasion of Mexico under the phony pretext that Mexican soldiers had fired on U.S. soldiers into U.S. territory. This pretext was known to be a crock by then-U.S. Representative Abraham Lincoln among many others. Lincoln introduced what were called his Spot Resolutions, demanding the Polk identify the precise spots on U.S. territory where Mexicans had fired. Of course he couldn’t do it, because the attacks never took place. The real reason for the war was to rip off vast swathes of Mexican territory to carve out new lands for the expansion of slavery, since slavery was prohibited in the North and the south needed new lands where they could take their slaves.
The war was successful. The U.S. annexed more than half of Mexico.
Many studies have shown that today’s “illegal” immigration of Mexicans and others from south of the border greatly benefits the U.S. economy. Living in New York City, I personally know of many undocumented immigrants from south of the border who are among the hardest-working people I have ever encountered, and who are pervasively exploited by their employers.
I put “illegal” in quotes because there is nothing illegal about reclaiming that which is rightfully yours. It may be de facto illegal under U.S. law but de jure it is absolutely correct.
Indeed, decades ago, Gore Vidal remarked that illegal immigration from Mexico represents a worthwhile and commendable effort by Mexico to reclaim the lands that were stolen from them. I agree with Vidal and I applaud Mexico in this effort, and wish it all the success in the world.
And I hope the first place they raise the Mexican flag is Santa Monica.