Texas became the 28th U.S. state

On 29 December 1845, President James K. Polk signed the measure admitting Texas to the Union as the 28th state. It was an unusual path to statehood: rather than a treaty needing a two-thirds Senate majority, Congress used a joint resolution that required only simple majorities in each house.

Texas arrived not as a territory but as a former sovereign nation. After winning independence from Mexico in 1836, the Republic of Texas had governed itself for roughly nine years, electing Sam Houston as president while many of its citizens pushed for annexation.

Joining the United States proved combustible. Mexico had never recognized Texan independence, and the disputed southern border helped trigger the Mexican–American War months later, in 1846. A republic that spent nearly a decade alone thus folded into the Union — and dragged two nations into open conflict almost immediately.