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Oregon Territory: In 1846 the Oregon Treaty was signed between the US and Britain to settle the boundary dispute
Mexican Cession: With the Treaty of Guadalupe Hidalgo, Mexico ceded over 525,000 square miles of territory to the United States in exchange for $15 million and the assumption of Mexican debts to American citizens, which reopened the slavery issue.
Gadsden Purchase: The Gadsden Purchase is a roughly 30,000 square-mile region of present-day southern Arizona and southwestern New Mexico that was acquired by the United States in a treaty signed by American ambassador to Mexico James Gadsden on December 30, 1853
Disputed Texas Territory: The Tyler-Texas treaty, signed on April 12, 1844, was framed to induct Texas into the Union as a territory, following constitutional protocols. To wit, Texas would cede all its public lands to the United States, and the federal government would assume all its bonded debt, up to $10 million.
Lonestar Republic: At San Jacinto on April 21, 18 36 , a band of Texan volunteers under General Sam Houston defeated the Mexican army, and captured Santa Anna. Texan independence was achieved. An election was held and Sam Houston was chosen president of the " Lone Star Republic ."
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