Florida forced Spain to cede this and other Gulf Coast

With the new autonomy, attitudes towards slavery changed; a clause in the Constitution protected the slave trade until 1808. Northern states abolished slavery between 1780 and 1804, leaving the southern slave states as defenders of the "peculiar institution." The "Second Great Awakening", which began around 1800, made the evangelical churches one of the main forces behind several of the reformist movements of the time, including abolitionism.31     Map of the territorial expansion of the country In 1803, the purchase of Louisiana from France during the term of President Thomas Jefferson almost doubled the size of the nation,32 at the same time that the Anglo-American War of 1812 further strengthened nationalism among the population. Defeated by the United Kingdom and after his second and final abdication to the French throne in 1815, Napoleon Bonaparte attempted to escape to the United States, then a rival of the United Kingdom, but was captured by British forces and deported to Saint Helena. In 1819, a series of military raids in Florida forced Spain to cede this and other Gulf Coast territories.32 The Trail of Tears in the 1830s exemplified the Indian Removal policy that stripped several indigenous peoples of their land. The United States annexed the Republic of Texas in 1845, during which time the concept of Manifest Destiny became popular.33 In 1846, the signing of the Oregon Treaty with the United Kingdom granted the country the current northwest territories.32 Two years later, victory in the Mexican War led to the cession of California and most of the present-day Southwest.32 The gold rush of 1848 and 1849 further stimulated westward migration and new railroads. They facilitated the relocation of settlers and increased conflicts with Native Americans. Over half a century, up to 40 million American bison were slaughtered for their hides and meat to facilitate the spread of railroads. The loss of buffalo, a primary source of food for the Plains Indians, was a mortal blow to many Native cultures.