On this day in history, Texas was admitted to the United States as a slave state.
The former Republic of Texas entered the Union as the 28th state on December 29, 1845, after Congress approved annexation by joint resolution earlier that year. Texas was the only state admitted through a treaty process, though annexation itself was enacted by Congress rather than ratified by the Senate.
Texas had declared independence from Mexico on March 2, 1836, and sought annexation to the United States the same year. The effort was rejected during the administration of President Andrew Jackson, with U.S. officials wary of intensifying sectional conflict over slavery and of provoking Mexico, which had abolished slavery and refused to recognize Texas independence.
Annexation returned as a major issue in the early 1840s. President John Tyler pursued annexation in 1843 and 1844, including negotiations that produced a treaty of annexation signed in April 1844. The Senate rejected that treaty in June 1844.
After the 1844 election, Tyler urged Congress to take up annexation through a joint resolution requiring simple majorities in both houses. Congress passed an annexation measure, and Tyler signed it on March 1, 1845. Texas accepted the offer and adopted a state constitution, and President James K. Polk signed the measure admitting Texas on December 29, 1845.
Texas formally joined the Union on Feb. 19, 1846. A dispute with Mexico over the Texas border, including contesting claims to the Rio Grande and the Nueces River, escalated after annexation and contributed to the outbreak of the Mexican-American War in April 1846.
