It's interesting to think about but I suspect that strangemaps got the part about total annexation wrong.

American politicians of the early nineteenth century -- hell, Americans in general -- were explicitly, overtly white supremacist, white nationalist in a way that's hard to appreciate for people who were brought up in the post-civil rights era.

To people of that mind-set, Mexicans were "mongrels" and therefore, not suitable citizens of the (white) republic.

If I remember correctly, there were a few attempts to annex Cuba which floundered because of Cuba's pigmentationally incorrect population. And more than a little bit of the Anti-Imperialist movement of the 1890s-1900s was racially based. They opposed the colonization of the Phillipines and Puerto Rico not out of any respect for those people's rights of self-determination; they simply didn't want large numbers of brown-skinned people to be incorporated into America.

That said, I imagine that it could have triggered the Civil War much earlier. The North and South kept the peace by designating this territory as non-slave and that territory as slave. How would the two have divided up the newly conquered Mexico? Would that have even been possible, given the geographical distance and (likely) resistance of millions of Mexicans?

It would have been too much to govern and stretched what was basically a volunteer militia way past the breaking point (remember, there was no Federal income tax to fund these kinds of wars.) European interest in the Americas was resurging right about that time - the various Treaties of Paris were holding up well enough that the crowned heads were starting to poke their heads out of their turtle shells and look around the world again - and there's no way the US would have been able to hold on to all that land.

There was indeed an "All Mexico" movement in the US, from Manifest Destiny adherents who wanted to annex all Mexico; and it was indeed resisted on explicitly racist grounds.

Gen. Grant really hated the Mexican-American War, incidentally: " "Generally, the officers of the army were indifferent whether the annexation was consummated or not; but not so all of them. For myself, I was bitterly opposed to the measure, and to this day regard the war, which resulted, as one of the most unjust ever waged by a stronger against a weaker nation. It was an instance of a republic following the bad example of European monarchies, in not considering justice in their desire to acquire additional territory."

Also, sounding familiar to followers of the current presidential campaign, he said, "The Southern rebellion was largely the outgrowth of the Mexican war. Nations, like individuals, are punished for their transgressions. We got our punishment in the most sanguinary and expensive war of modern times."

Heh. Modern.

Ever notice that? Everyone lives in "modern" times. Fifty years ago the current modern times will be looked at as "quaint".

Ever notice that? Everyone lives in "modern" times. Fifty years ago the current modern times will be looked at as "quaint".

You know, Doohickie, I think I'm hearing a MetaChat post in those words . . .