The Joint Resolution for Annexing Texas was a legislative measure passed by the U.S. Congress in 1845, which facilitated the incorporation of the Republic of Texas into the United States as a state. This resolution stemmed from ongoing tensions regarding Texas's independence from Mexico and the desire among many Americans for territorial expansion, known as Manifest Destiny. It was a significant step in U.S. history, marking the expansion of American territory and intensifying sectional tensions over slavery.