How did the US and Mexico negotiate the far western borders in 1848

Factual Questions
1

How did the US and Mexico arrive at the far western boundary lines in the Treaty of Guadalupe Hidalgo (2/2/1848)?

In 1773, Spain marked a boundary between Baja and Alta California around Ensenada as the boundary between the Dominican and Franciscan Missions. In 1804, apparently Spain made formal the boundary between the states of Baja and Alta California, but I don’t know where the line was. I can only assume the same line marker was used near Ensenada. Perhaps the border was established at its current location before the Mex-Am war? If so, why was it put there?

The Treaty used the Gila River and a line from the intersection of the Gila and Colorado Rivers to a spot 1 league south of the southernmost point of San Diego Bay.

I understand the US was not interested in taking all or too much of Mexico as a result of the war essentially due to cultural differences and potential slavery issues, so they wanted to draw a line somewhere.

I also understand the Baja peninsula was sparsely populated and desert, but so was much of the area actually annexed.

  1. Why didn’t the US annex Baja? I know William Walker took over Baja on his own accord in 1853, after the war, with only 45 men, but was quickly acquitted of crimes in a California court due to the prevailing ideas on Manifest Destiny. If those ideas were so strong, why didn’t they lead to US annexation of Baja in the first place? The ideas were strong but not THAT strong?

  2. Why didn’t the US, at the very least, annex the mouth of the Colorado River at the Sea of Cortez or Gulf of California along with some agreement as to rights of passage and use of the Gulf? I would think the US would want that as a potential natural resource and potential port while denying Mexico a potential strategic military point in terms of river access.

  3. Why didn’t the US and Mexico simply keep the established Spanish border at Ensenada between Baja and Alta California? If it was a given that Mexico would keep Baja, did Mexico want to ensure physical connection between the mainland and Baja?

  4. Why didn’t the US take the Tijuana area? Why stop at just barely taking enough to get the entire San Diego Bay plus a bit? If old boundaries between Baja and Alta were being disregarded anyway, I would think the US would want to take the Tijuana River and Valley pretty much adjacent to the San Diego Bay area in that they are basically connected as a geographic region. It was basically just ranch land at the time and not a big urban area filled with Mexicans, so I can’t see a cultural barrier to the US wanting to take Tijuana.

2

Adding the term “negotiate” to my Google search, I find this…

How was Mexico in a position to demand anything?

and this

3

and this

What happened to the Mission markerset in 1773?

4

Hmm…

5

1787 map showing the line

6

Location of Misión San Miguel Arcángel de la Frontera

According to this, Rosarito Creek is at 32° 19’ N 117° 00’ W, which is a tad north, here.

7

Link

So the mission line apparently went out the window with the merger and then a new split in 1804. So the old mission line was probably gone and not a basis for much of anything by the time of the Mex-Am War.

This is starting to come together. I wonder why the 1804 split and how they drew the line then.

8

… and why was the US so quick to end the war at that time and just drop Baja from its demands?

9

According to the Library of Congress, the map used for negotiating the Treaty sets the Alta-Baja border south of the current border.

So it appears the parties drew a new line, essentially maintaining the traditional Alta-Baja partition. This partition moved around a bit in the past but generally stretched back to the old Mission days. They negotiated adjustments to the exact partition to simply ensure, at a minimum, inclusion of San Diego Bay for the US and a “land bridge” connecting Baja to mainland Mexico. That was “good enough” for the US, as it appears Polk was getting impatient and wanted an agreement 6 months prior.

10

Also, I guess I can make a WAG as to the cost-benefit of acquiring Baja:

Essentially, it’s a strip of mountains and desert. There isn’t mush in terms of a major port, except by La Paz and Esenada, and La Paz is a helluva long way from the rest of the acquired territory.

Access to the Sea of Cortez doesn’t offer much that you don’t already get by taking San Diego and San Francisco; it’s not very effective to ship things up the Sea of Cortez when you can just ship to San Diego.

Although it doesn’t appear it would have been difficult for the US to take Baja, for whatever reason, Polk wanted it over months prior based upon what he decided were the “major objectives.” I can only assume these objectives include getting a Pacific presence with a couple major ports… done deal. Baja would have just been icing on the cake and not really worth the additional trouble, especially considering the US took $5M off the table as an offset.

11

Weren’t there some real political maneuvering going on that lead to this treaty. I can’t find my copy of James McPherson’s “Battle Cry of Freedom” which mentions it in the beginning but essentially President Polk, whose term was expiring (he was elected promising only to serve one term) got impatient with Nicholas Trist and tried to get him withdrawn because Polk decided he wanted more. Trist ignored him and got a treaty. The Senate had people who wanted more and others who wanted less but enough were happy enough to ratify it. As it was, the opposition party (Whigs) ran one of the heroes, General Zachary “Old Rough and Ready” Taylor and won the election anyways.

The Mexican-American war was controversial in its day. Ulysses S Grant in his “Memoirs” calls it the most unjust war ever waged by a strong nation against a weaker one. One Whig in Congress remembered how the Federalists disappeared after opposing the War of 1812 and sarcastically announced he was now if favor of pestilence and famine too.

As it happened, the Americans weren’t happy with the final borders and negotiated the Gadsden Purchase to get southern Arizona (including Tucson) and New Mexico.

12

Because the war was expensive as all get-out. And most Whigs were opposed to the war, and had done well in the Congressional elections of 1846, so it was starting to look like a political albatross.

Mexico was certainly in a weak position in 1847, but not completely helpless. The Polk administration needed a treaty (else the expensive occupation would drag on forever), and they needed a functioning Mexican government with which to negotiate it. If they demanded even more, there was risk that Mexico would dissolve into anarchy–bad for the US, as we saw later during the Pancho Villa era.

As it happened, Polk did up his demands in April 1847. He recalled Trist and intended to send another commissioner who would demand Baja and much of what is now northern Mexico. Trist realized the danger of this course, ignored his recall, and negotiated a treaty satisfying Polk’s original demands. When the treaty arrived in Washington, Polk decided it was good enough and sent it to the Senate, which ratified it despite Southern complaints that it was too soft and northern Whig complaints that it was too severe.

13

Thanks. Your input helps as does this article.

14

Bearflag
Thank you for a nice piece of research. You might be interested in an exhibit of historic maps of the US-Mexico border that is now showing at University of San Diego. Search for the Trans-Border Institute and they have the details. One of the speakers at the reception on 4/21 is talking about Conde’s personal map that he used to negotiate the Gadsden Purchase.

15

Thanks. I wish I could attend.

16

This. We tend to lose site of this because the Treaty of Guadalupe kind of tends to overshine it.

I tend to get the idea that “highly devisive” is much more descriptive than “controversial.” The Democrats (particularly in the South) saw this as an easy route to expand their power in Washington, by acquiring new slave territories. This war had a lot to do with provoking our Civil War. All-in-all, though, I’m not in favor of giving the land back to Mexico!

It’s kind of interesting being able to share the Mexicans’ perspective in this, as well. For example, despite the unjustness of the war, I’m still proud of the Marines, and can shed a tear for them while standing within the the actual Halls of Montezuma from their anthemn, while at the same time having great respect for the bravery of the Niños Heroes who defended that very castle.

17

While I, to, consider the war unjust, we also can’t entirely leave out Mexico - or at least Santa Anna’s - complicity in starting it. Santa Anna was a nasty customer, at best an enlightened despot and at worst a power-hungry traitor. He never made a deal he didn’t break, and his military reputation was grossly inflated. While he wasn’t incompetent by any means, he wasn’t particularly great at anything except persuading people iof his greatness.

He made an enemy of the Church largely because it looked upon him with justified suspicion, threw out the Jesuits who had done so much for Mexico and particularly its native peoples, turned the Texas issue from a small problem into a major crisis, set the spark for war with the U.S., set taxes so onerous sections of Mexico revolted, and then betrayed his own country. hell, by the 1870’s, he was still . The inadvertent introduction of chewing gum was his biggest success, and it wasn’t even really his!

I don’t think much of Polk, but Santa Anna was something else and almost the entire mess can be laid at his feet. I do not think the war would ever have happened had Santa Anna not been on the scene.

18

All true, but I’ll say this for the man - one of the causes of the war was that he wanted to enforce Mexican law in Texas, including the ban on slavery. As bad a fellow as Santa Anna was, on this issue he was on the unambiguously correct side.

19

I’m not sure I understand this. Mexico had already outlawed slavery within it’s borders. (That was a main reason that Texas broke away – Texans wanted to keep slavery going.) Are you saying that territories from formerly-slavery-free Mexican areas would automatically become slave states in the US, because they were south of the Mason-Dixon line? But that was already a controversial question, as for example in Kansas.

20

We also forget that Mexico was both in a state of near anarchy and near bankruptcy at the time. Although the Mexican Politicos made noises about the treaty, the nation badly needed the infusion of cash.

And there also the point that Mexico had political control over that area for less than a generation, and that control was extremely tenuous.
“The northern states grew increasingly isolated, economically and politically, due to prolonged Comanche raids and attacks. New Mexico in particular had been gravitating toward Comancheria. In the 1820s, when the United States began to exert influence over the region, New Mexico had already begun to question its loyalty to Mexico. By the time of the Mexican-American War, the Comanches had raided and pillaged large portions of northern Mexico, resulting in sustained impoverishment, political fragmentation, and general frustration at the inability—or unwillingness—of the Mexican government to discipline the Comanches.”

Mexico had but tenuous control of that territory, (and others, see "Republic of the Rio Grande " and others). The Government was unstable, unpopular and bankrupt. It’s legal and moral claim to areas which it had little control over and little support from the populace. The people- by and large- did not consider themselves “Mexican” and in many cases greeted the Americans as liberators, not conquerors.

In some cases, Mexico didn’t really have any real political control until the 1835 “Constitutional Bases”, whereby the federal republic was converted into a unitary one, and the nation’s states (estados) were turned into departments (departamentos). And the Mexican American war started in 1846. That’s about 11 years. Things were very fluid and chaotic from 1821 (Treaty of Córdoba) until 1835 and even after, with several areas declaring themselves independent.

In any case, the residents were mostly not Mexican, and did not want to be governed from Mexico.

Here’s an earlier thread:
http://boards.straightdope.com/sdmb/showthread.php?t=530877&highlight=Guadalupe&page=2

And anotehr post by me:
*But of course AZ was only part of Mexico for about a generation, and in fact the Californios deeply resented being part of Mexico. Before Mexico, it belonged to Spain for around 70 years. Before that AZ belonged to the one of the Pima indian tribes, likely the Sobaipuri- for about 100 years. They took it from the Hohokam, probably, although its possible it was a peaceful merge. The Hohokam existed in that area for around 1400 years. Who’s the rightful owner then?

Even while AZ was technically part of Mexico, Mexico’s control was tenuous- most of the time the Apaches and other tribes ruled the area. Note that in 1831 Tuscon only had 465 “Mexicans” while the same census listed rather more Indians.

While it is true that the Americans had Mexico at the point of a gun, Mexico was only too glad to accept the very generous $18,250,000 that the USA paid for those territories, (generally considered more trouble than they were worth) as Mexico was pretty well bankrupt. Not quite “taken by force”, although certainly the threat was there. My guess is that Mexico likely would have taken the cash war or no war.

Per wiki “There were approximately 80,000 Mexicans in the areas of California, New Mexico, Arizona and Texas during this period and they made up about 20% of the population” (and there were quite a few Americans living there too, as well as Natives). So,in fact the “Mexican” blood in that area was pretty damn thin.

The Natives- as usual- got the real hosing.*
http://boards.straightdope.com/sdmb/showthread.php?p=11298017&highlight=mexico#post11298017