in the 1840s waves of Americans started to move Westward and by 1860 some 4.3 million Americans had crossed the Mississippi River spread out across the Great Plains had climbed over the Rocky Mountains and they were now residing even as far west as the Pacific coast how Americans got there was a matter of where they were headed this map shows you the principal Western Trails setting out from the Midwest of the United States across the Great Plains into places like Santa Fe or into places like Northern California or even as far west as Oregon City in the Oregon Country depending on who you were or where you wanted to go this was how you were going to get there and by the end of uh the 1806 by the by the time of the 1860s uh as I mentioned over 4.3 million people had made this Trek now Westward Expansion was especially critical to Southerners many of whom wanted access to cheap and fertile lands in the west of which they could grow cotton and using of course their enslaved workers then Southerners had long enjoyed a disproportionate control over National politics because of the U.S Constitution's permission of three-fifths of the state's enslaved population to be included whenever it was determined the number of congressional seats or Congressional votes that a state would get now of course because out of this disproportionate control over national uh political National politics had also resulted in nine of the first 12 presidents being Southern born Southerners held most of the leadership positions in the U.S Congress and yet by the 1840s uh southern political power had begun to wane as the population of the industrializing Midwest and of the Northeast grew more rapidly than the population in the South which increased those regions representation in Congress what I just described is shown to you here on this graph in the Years 1830 1840 where you can see that [Music] um uh the number of additional votes uh allowed through this three-fifths Clause of the U.S Constitution has begun to to Crest and over a 20-year period as slavery was not expanding which I'll briefly talk about here in just a second this disproportionate control had appeared to be contained um and it was out of this containment that southerners wanted new Western lands in order to boost uh the pro-southern representation in Congress and thus ensure that Northerners could not affect slavery through any type of hostile legislation and such motives made the addition of new western territories then a flash point of the sectional debate uh you know because what would these territories be would they be free territories would they be slave territories uh and so as Americans made their way west They Carried with them kind of their their preconceived notions of what they were wanting the West to be Northerners of course were hoping that the West Was going to be very similar to what they lived uh in the environment they lived in terms of a free Society but southerners wanted of course the push West as well looking for cheap and fertile lands places like Texas which we've already talked about but they were interested in pushing even further west for cheap land fertile land and hopefully expanding slavery for political purposes now in 1845 a New York newspaper editor by the name of John O'Sullivan came up with a catchy name that caught America's aggressive Spirit of Westward Expansion in the 1840s our Manifest Destiny he said is to overspread the continent allotted by Providence for the free development of our yearly multiplying millions and for the great experiment of Liberty and thus the idea of manifest destiny now had a name and now the idea of manifest destiny implied that the United States had a god-given mission to extend the Christian Republic and a capitalist economy from sea to shining sea and perhaps Beyond and the sentiment of course flattered Americans vanity and it offered them a powerful albeit self-serving vision of the nation's future and then of course it provided a justification for the aggressive foreign policy initiatives that were pursued by the United States in the 1840s in fact Manifest Destiny helped delay the groundwork for a war with America's neighbor to the South Mexico now the offshoot of this idea of manifest destiny was the question of whether or not to Annex the Republic of Texas to the United States and Texas leaders such as Sam Houston were of course frustrated that their independence which was so hard fought for had not actually led to annexation in Texas at this time there was no infrastructure there were no banks there were no schools there were no Industries in Texas remained for the most part a frontier community of scattered log cabins with very few cities it also had no money it had a rising national debt and simmering tensions with with Mexico who insisted that the Republic of Texas was no Republic at all and actually still remained part of Mexico and thus Mexico was still at war with Texas in short Texas was at a precarious position now efforts to Annex the Republic of Texas to the United States were generally supported by Southerners on account that it would expand slavery and it would add a large and fertile state to the union for example in 1843 Secretary of State at the time our old friend John C Calhoun uh had sent to the senate for ratification a treaty that would Annex Texas but it was soundly defeated by a vote of 35 to 16. and the reason it was defeated is that Northerners and Northern Senators uh refused to add another slave state to the Union uh for out of a desire of not seeing slavery expand anymore since we since the United States had uh uh put in place the the provisions of the Missouri Compromise uh still there were others that feared annexing Texas might spark a war with Mexico but for the most part the northern protest against the annexation of Texas centered on Northerners um not wanting to see slavery expand Beyond its current borders and this uh is an excerpt from a very famous protest that was lodged by a group of Northern uh congressmen both senators and representatives in the house uh talking about it was a protest against the annexation of Texas and I've pulled out a couple of the pertinent passages here to illustrate kind of the thought process of most of these Northern congressmen who are then a reflection of course of the northern people they say in this protest that the forcible seizure of Texas is a validly and entering wedge and entering wedge to an extended series of Conquest repeating an oppression to overthrow the three states and make an undue preponderance against them particularly in the election of the Senate and the executive by indefinitely extending the slave representation this is their way of saying that the Three-Fifths Compromise has resulted over the years an undue representation a disproportionate representation and control by Southerners over National politics and adding Texas would only be allowing this to continue uh and so Northerners were for the most part against the annexation of Texas because they did not want to see what they had come to regard as the slave power uh which is this disproportionate control over National politics they did not want to see it expanded even further um and so there it was you know the Republic of Texas was a hot button issue uh for a period of about 10 years from the uh conclusion of the Texas Revolution in 1836 until ultimately Texas was annexed in 1846. um now just sticking with this annexation of Texas question we also during this time had a very significant presidential election which took place in 1844. in that year both the Democrats and the Whig parties had hoped to keep the divisive issue of Texas out of the presidential campaign that year and the two leading candidates for president that year or the president assumptive candidates Henry Clay of the Whig party and Martin Van Buren of the democratic party Martin Van Buren by the way was a former president he had won the 1836 election but lost re-election in 1840 he was back now and was presumed to be the Democratic Party candidate in 1844 as Henry Clay was presumed to be the candidate for the Whig party of that year now both of these gentlemen had agreed that adding Texas to the union would be a mistake and it would probably cause a very sectional a very dangerous sectional crisis of the Union uh and this position ultimately cost Martin Van Buren the support of Southern Democrats who staged uh at the party convention that summer who they staged the coup and essentially ensured that they nominated somebody other than Martin Van Buren and the gentleman they nominated in 1844 was the James K Polk who was a former speaker of the house and a former governor of the state of Tennessee now the reason the Democrats went with him and the reason Southern Democrats forced the Democratic party's hand in nominating James K Polk because that Polk was an aggressive expansionist who insisted upon the being nominated that the Democratic party alter its platform to include you guessed it the annexation of Texas and thus Polk became and then the first kind of dark horse or unexpected candidate to win a major party nomination for president of the United States and this of course then set up a showdown between James K Polk of the democratic party and the Whig parties candidate who was in fact Henry Clay and this election between the two individuals proved to be one of the most consequential elections in American history because of what it led to um now let's talk about this this election just real quick by promoting southern and western expansionism uh Polk and the Democrats actually had a very winning formula very good formula to win in this election and um their support of Western expansionism in this Manifest Destiny idea actually forced clay to alter his position regarding Texas at the very last minute of this election but it was too late and ultimately in a 100 to 70 100 to 5 electoral Victory Polk actually secured the presidency now I do want to mention here it's not worth uh remembering outside of just just to think about but this election was actually decided by a single state and that was the state of New York which went for Polk clay lost this state by over 5 000 votes uh by just over five thousand it was a very slim margin right and his defeat there was in large part due to his last second change of heart about the annexation of Texas when he when he unexpectedly at the last moment came out in favor of annexation of Texas he actually hoped that would be enough to carry him to Victory but in a strange Twist of irony it actually cost them the election because when he came out in favor of the annexation of Texas it drove a lot of supporters in the state of New York towards a third party candidate of the Liberty party uh whose candidate received over 15 000 votes in the state of New York now had Clay won New York he would have actually won the election by seven electoral votes now before Polk could be inaugurated uh Texas ultimately was annexed to the union on March 1st 1845 by then President John Tyler who was able to convince Congress to support a joint resolution uh a little bit about John Tyler he he was never supposed to be president he was the vice president for the president of the United States who won in 1840 that gentleman's name was William Henry Harrison uh the problem is at Harrison's inauguration address and some of y'all may know this story already uh it was very cold very windy um horrible conditions in Washington DC when Harrison gave his inauguration address is it not going to race in his inaugural address was hours long in the driving snow and sleet and cold and wind and he didn't wear a top hat he didn't wear a heavy coat and they actually caught pneumonia and his presidency lasted only one month uh and he died in office and that's when John Tyler took over and nobody liked John Tyler Or democrats didn't like him Whigs didn't like them and the only thing he really ever did is President that's of note is he was able to convince Congress to support a joint resolution to Annex Texas which required less votes and was able to overcome the northern obstacles to annexing Texas turns out this would be his final action as president of the United States now the annexation of Texas uh this event immediately caused tension between the United States and Mexico because Mexico saw it as the theft of part of its Nation uh but on December 29 1845 uh the official annexation of Texas took place it joined the union it of course uh joining the union meant that slavery expanded because uh slavery was allowed in the Republic of Texas it was allowed in the province of Texas before it was an independent nation and since the State Constitution that Texas wrote upon being annexed uh was written by Texans it of course was going to be a state that allowed for slavery now the reason the annexation of Texas caused tension between the United States and Mexico goes back to the end of the Texas Revolution now at the end of the Texas Revolution as part of uh Antonio Lopez de Santa Anna's agreement with Sam Houston after the battle of San Jacinto a treaty was forged between Texans between Texas and the Mexican Government which was Santa Ana and this Treaty of May 14 1836 was known as the Treaty of Alaska and if it was of course supported by Antonio Lopez de Santa Anna in exchange for his life the problem is is that by 1845 Santa Ana had been deposed as president of Mexico he'd been forced into Exile and the new Mexican government the Republic of the Mexicana denounced the Treaty of Velasco said it was illegitimate that it was formed under duress that Santa Ana did not speak for the Mexican people and so the Republic of Mexico never acknowledged uh Texas is being an independent republic and now that it's been annexed to the United States it's seen by Mexico as a very aggressive step towards possible War because it was seen by Mexico as essentially theft of a giant portion of its country and absorbed them into the United States uh so more on that in a little bit but I want to talk just briefly about the goals of President James K Polk uh in terms of expansion uh because the theme of this little lecture here is an expanding Nation now once he was installed in office Polk he was a president in a hurry and his top priority was of course territorial expansion because that's largely why he'd won the nomination uh by the Democrats and it's largely why he won the election now his goals were that he wanted to add Oregon he wanted to add California and he wanted to add New Mexico to the union and when it came to Oregon in the summer of 1946 the Oregon country is this area way up there in the top right or top left uh in June of 1946 he ended up settling a long-standing border dispute with the British over the borders of the Oregon Country which had been divided along the four the 40 uh ninth parallel this area of North America had been in dispute with the British for a very long time but what in what was known as the Oregon Treaty of June of 19 or 1846 Polk was able to deliver on a campaign promise to settle this dispute and to solidify the borders of not only the Oregon Territory but also the entirety then of uh the United States Northern border now the other two territorial goals however they would not be so easy and as it turns out if Polk wanted California if Polk wanted the New Mexico territory they were probably going to have to be taken as a result of War now those two territories formed that gray area that there on this map called Mexico