Grey-



Mexico had been actively encouraging colonization at the time, chances are this would not stop, but would change if Mexico won.



For example, European colonization might have increased, while stronger borders might have kept American settlers out. Additionally, Mexico would probably have sought more settlers from RC countries, because they would be considered easier to integrate into a North Mexico that was to remain Mexican.



GB might actually assist this by making it easier for the Irish to emmigrate to Mexico. Additionally, German and Central European settlers might also have come in, particularly after the unrests of 1848.



This having been stated, I think that even under these conditions, the chances are the US would eventually have gone to war with Mexico over Texas, if only because the South would see Texas as a 'natural' areas to expand into to counter the growing anti-slavery territories.



Additionally, with the US focussed more in the 1840's on the Oregon Territory, it is likely that the US would have insisted on a bigger piece of it, maybe most of British Columbia and Vancouver.



My real question is now this, we have the South actively encouraging westward movement to counter the number of free states, their focus is quite natuarlly going to be on Texas because of its proximity. Does the South or a group of Southerners force a war through the wide spread

publication of atrocities and incidents between American Citizens and Mexican Border Guards?



I think it does, at least eventually (maybe around 1855). This might provoke a war that included Great Britain, but I do not believe that GB will want to get involved in a North American war at this time, there is just too much on its plate. Therefore, it is probable in this scenario that a Mexican War would occur, the US would win it, and Texas would be part of the settlement of that war.



Conversely, this action is going to have a dramatic effect on the ACW for two reasons. First, neither the North nor the South would be willing to spill each other's blood after so recently serving together, and second, a Texas more heavily settled by Irish/German/Mexican farmers is very different than OTL Texas of the same period.



Therefore all action on the slavery issue is put off for a while, as the US continues to keep itself together with compromise after compromise on the issue. When it finally does erupt into the open, say between 1870 and 1875, the Northern juggernaut is just to much, particularly if the West (read Texas) is much less sympathetic to the "Great Cause".