Manifest Destiny: Florida, Texas, and Oregon

General Andrew Jackson's unauthorized invasion of Spanish Florida in 1818 exposed Spain's inability to defend the territory, and Secretary of State John Quincy Adams used this leverage to negotiate the Adams-Onis Treaty (1819), through which Spain ceded all of Florida in exchange for the United States renouncing any claim to Texas. Once in office, Jackson championed the Indian Removal Act of 1830, which authorized the forced relocation of Indigenous nations of the Southeast — including the Cherokee, Choctaw, Chickasaw, Muscogee-Creek, and Seminole — to territory west of the Mississippi; although the Cherokee won a favorable Supreme Court ruling in "Worcester v. Georgia" (1832), the federal government enforced removal by military force regardless. The resulting forced march of the Cherokee nation in 1838-1839, known as the Trail of Tears, killed an estimated four thousand to eight thousand of the roughly sixteen thousand people displaced, from disease, hunger, and exposure.