Could the US have gotten more from Treaty of Guadalupe Hidalgo?

[colonel]

Assume the United States negotiators had pushed their advantage to the limit in the Treaty ending the Mexican American War. How much additional territory could they have obtained? Baja, Sonora, Chihuahua, or some combination thereof? The populations of those areas were sufficiently sparse that the United States would have little concern about absorbing Mexican Catholics. Even assuming they could have gotten the Mexicans to agree, I think it's possible they would have trouble getting free state Senators to sign off absent some assurance the territories would not be eligible to be admitted as slave states. If it does happen what effect does this have on the Civil War and future Mexican American relations?

 

[Analytical Engine]

Yes. In fact, that was the plan - however the negotiator decided to go for the OTL Mexican cession.

As to the Civil War - well, Mexico had already banned slavery, and it will take a while before any of the new Mexican lands would be developed enough to be profitable for any potential re-introduction.

 

[Byz]

The primary obstacle to this is internal American opposition, mainly from the north and proto-republicans. Among other names, Abraham Lincoln was an outspoken critic of the Mexican-American war, arguing it was a war to expand slavery the south forced on the rest of the nation.

Undoubtedly more could have been gained. Mexico had by this point been decisively defeated, and never had a strong grip on any of its northern territories. The plan with new territories acquired would undoubtedly have been to make them slave states with a similar situation developing to that of Texas. Unlike California or the Plains, I don't see significant free soil movement into these lands. Instead like in OTL South Texas you'd see southern planters move in and take control of vast estates, populated primarily by Norterños. Unlike in Texas I'd expect much money organized and sustained resistance to this takeover by local elites, simply because of the greater numbers involved. There is now a greater Spanish speaking population under American control than OTL, a population already used to carrying out resistance to attempts to put them under the boot of a centralized republic.

The dynamics are sure to be complicated

 

[Mav12]

IIRC there was a plan going around for the US to annex all of Mexico. It was shot down because of racism in a lack of desire to add so many Mexicans to the population.

 

[colonel]

The primary obstacle to this is internal American opposition, mainly from the north and proto-republicans. Among other names, Abraham Lincoln was an outspoken critic of the Mexican-American war, arguing it was a war to expand slavery the south forced on the rest of the nation.

Undoubtedly more could have been gained. Mexico had by this point been decisively defeated, and never had a strong grip on any of its northern territories. The plan with new territories acquired would undoubtedly have been to make them slave states with a similar situation developing to that of Texas. Unlike California or the Plains, I don't see significant free soil movement into these lands. Instead like in OTL South Texas you'd see southern planters move in and take control of vast estates, populated primarily by Norterños. Unlike in Texas I'd expect much money organized and sustained resistance to this takeover by local elites, simply because of the greater numbers involved. There is now a greater Spanish speaking population under American control than OTL, a population already used to carrying out resistance to attempts to put them under the boot of a centralized republic.

The dynamics are sure to be complicated

Perhaps this lengthens the American Civil War. This in turn would make the French incursion in Mexico somewhat more successful at least until the Franco-Prussian War.

 

[dfl_90]

The short answer is yes. Even though it coerced through war, the Mexican government acknowledged that it exercised very little control over it's northern territories and acquiesced to the American demands. Had Trist not acted as independently, it's very likely that Baja California would've been purchased as well, and probably with little fuss from the American side. There were also proposals to push the rest of the border further south, perhaps somewhere in the ballpark of the 26th parallel, but that was controversial and didn't appear likely to make it through the Senate. Sectionalism and concerns about absorbing Mexican Catholics played a part in it, but more generally Polk had already laid out the American war aims, which roughly corresponded with the modern border plus Baja California.

 

[Byz]

IIRC there was a plan going around for the US to annex all of Mexico. It was shot down because of racism in a lack of desire to add so many Mexicans to the population.

My understanding is that though racism might have played a role, the greater concern was fear of this being a power play by the South to create more slave states.

Ultimately I don't think the US could conquer and hold Mexico proper. They could take a whole lot more land, but once you get to the heavily populated parts it would be all but impossible. It would be basically Mexico becoming a colony of the United States, which the US of 1848 didn't have the means to control continuously. Nor do I think either surrounding nations or actors like the British and French would tolerate such a thing, leading to plenty of support for Mexican rebels who will inevitably break free.

 

[Analytical Engine]

I think the US could have taken the northern tier of Mexican states, plus Baja, due to their relatively low population, but they wouldn't have wanted too much land because racism and anti-Catholic tendencies.