JAMES K. POLK. The acquisition of Texas, New Mexico, and California took place over a period of about 10 years and three presidents. It started in 1836 with President Martin van Buren who attempted to annex Texas but did not want a war with Mexico.
President van Buren's successor John Tyler continued with van Buren's efforts and managed to create a Treaty of annexation in 1844, but did not get the necessary votes from the senate for ratification.
Then came President James K. Polk. President Tyler and President-elect Polk together were successful in obtaining the votes for the annexation of Texas in 1845. The succeeding events; the Oregon Treaty with the British in 1846 and the signing of the Treaty of Guadalupe-Hidalgo in 1848, lead the way for the acquisition of not only Texas, but New Mexico, California, Nevada, Arizona, Utah, Washington, and Oregon. This is considered to be the largest acquisition of land the United States has ever experienced.
