hello class today we will look at the concept of manifest destiny manifest destiny refers to the idea that it was America's destiny as a nation to span the entire continent from the Atlantic to the Pacific Ocean the modern map of the United States as we know it today did not exist until through purchases wars or treaties the United States acquired all the western territories there are several things that motivated Americans to move west as the population of the country began to grow demand for new farmland also grew some people sought religious refuge such as the Mormons who fled persecution in the east to finally settle in present-day Utah others went to California after gold was discovered there in 1848 whatever the reasons between 1800 and 1820 over 2 million Americans had migrated West and that number was continuing to grow the first major land acquisition was the Louisiana Purchase after the Revolutionary War at the western border of the United States only extended West to the Mississippi River and we still did not control the mouth of that River in 1803 President Thomas Jefferson agreed to buy the Louisiana territory from Frances Emperor Napoleon for the small price of fifteen million dollars the United States now owned all of North America from the Atlantic to the Rocky Mountains including New Orleans in the mouth of the Mississippi River Thomas Jefferson commissioned captains Meriwether Lewis and William Clark to lead a group known as the Corps of Discovery to explore and survey the territory joining the team as a translator and guide was a young Native American woman by the name of Sacagawea the Louisiana Purchase was important not only because it doubled the size of the United States but also the purchase gave the u.s. full control of the Mississippi River including the port in New Orleans and now on to Florida beginning in the early 1800s many runaway slaves and displaced Native Americans had fled into Spanish controlled Florida in order to capture the Runaways and to stop Native American raids into Georgia in 1818 American troops under the leadership of General Andrew Jackson invaded Florida in 1819 Secretary of State John Quincy Adams negotiated the Adams onís treaty in which Spain ceded or surrendered Florida to the United States and now we get free orange juice and Disney World beginning in the 1820s thousands of American families began to settle in the Mexican territory of Texas in 1830 Mexico closed Texas to further emigration by American settlers in addition the Mexican government also banned the importation of slaves into Texas this set off a war for Texan independence the war took place between 1835 and 1836 on March 6th my birthday in case you were wondering in 1836 Mexican forces stormed and defeated Texas forces at the Battle of the Alamo in San Antonio despite this defeat Texas independence forces led by Sam Houston were victorious at the Battle of San Jacinto starting in 1836 Texas was an independent republic until it was officially entered into the Union after Congress and exit in 1845 President James Polk won election in 1844 partly because he vowed to annex Texas despite the concerns that this would trigger a war with Mexico Polk also vowed to aggressively push American claims in the disputed Oregon Territory both the US and Great Britain claimed the region and in 1846 the two countries agreed to settle the Oregon question in the agreement the u.s. received all the Oregon territory south of the 49 degree latitude line until the 1840s the American West and Southwest was part of Mexico in 1846 it was reported that Mexican soldiers fired on American forces under the command of general Zachary Taylor President Pope used this as an excuse to ask Congress for a declaration of war the mexican-american war was fought between 1846 and 1848 by 1848 the United States had won the war and Mexico signed the Treaty of Guadalupe Hidalgo as a result of the treaty the United States had acquired present-day California Nevada Colorado Utah Arizona and New Mexico by 1853 the American government had acquired all the territory that makes up the present-day United States acquisition of western territory did lead to other controversies particularly with Native American tribes already living in the region as the u.s. continued to add territory it also brought up the divisive debate over slavery which would reach a boiling point throughout the 1850s [Music] you