Texas annexation

Admission of the Republic of Texas to the United States as the 28th state on December 29, 1845. Texas had declared independence from Mexico in 1836; after the Senate rejected an annexation treaty in 1844, pro-annexation candidate James K. Polk won the presidency, Congress passed a joint resolution in March 1845, and Texas ratified it. The annexation prompted the Mexican-American War in 1846.