1. President Thomas Jefferson
a. Anti-Federalist: usually weary of American expansionism
b. Louisiana Purchase
i. After Spain gave New Orleans to the French, Jefferson sent Monroe to France to buy the strategic land for $2 million ii. France about to engage in war in Europe and dealing with a slave revolt in Haiti, offered to sell the entire Louisiana Territory for $15 million and Jefferson accepted, even though he wasn't sure that the Constitution allowed for it iii. Congress quickly approved the treaty iv. Strengthened the United States because gave them complete control over the strategically crucial Mississippi River
c. Louis and Clark
i. Sent expedition to explore territory west ii. Encountered many new animals, plants, and Indian tribes iii. Strengthened the United States in that the West was no longer completely un-chartered territory, and knowledge was deepened after the countless scientific discoveries
2. President James K. Polk
a. Democrat who favored vast expansion at a rapid rate
b. Rallied for the immediate annexation of Texas, which Tyler accomplished right before Polk took office
c. Oregon Territory
i. Acquired from a treaty with Great Britain made peacefully in 1846 ii. Established current northern border for the region iii. Strengthened America because of more territory and greater control of the continent, less outside influence
d. Mexican-American War
i. Polk wanted to acquire the Southwest from Mexico ii. Mexico wouldn't sell the territory, so Polk provoked Mexican troops with the stationing of American troops and declared war iii. After a successful invasion of Mexico City and the war was over, Mexico signed the Treaty of Guadalupe-Hidalgo in 1848 ceding most of the modern Southwest over to the United States iv. Strengthened America