Anglo-American immigrants, mainly from the southern United States, began to migrate to Texas Mexicana in the early 1820s at the request of the Mexican government, which sought to increase the low population density of the lands on its northern border. The Anglo-Americans soon became the majority in Texas and finally, they became disillusioned with the Mexican authority. The state of Coahuila and Texas, a Mexican state of which Texas was a constituent since 1824, approved a plan for the gradual emancipation of slaves from the state in 1827, infuriating many of the slave-owning settlers who had moved to Texas from The USA. of the South and had lived in Mexico less than a decade. For these and other reasons, Texas declared its independence from Mexico, resulting in war with Mexico. In 1836, the fight ended and Sam Houston became the first president of the Republic of Texas, elected on a platform that favored annexation to the United States.
In August of 1837, Memucán Hunt, Jr., ambassador of Texas in the United States, presented a proposal of annexation to the administration of Van Buren. Believing that the annexation would lead to a war with Mexico, the US administration rejected the Texas proposal. After the election of Mirabeau B. Lamar, an opponent of annexation, as president of Texas in 1838 and the refusal of the United States to it, Texas withdrew its offer.
In 1843, President John Tyler came out in support of the annexation, entering into negotiations with the Republic of Texas to finalize an annexation treaty, which he submitted to the Senate. On June 8, 1844, the treaty was defeated 16 to 35, well below the two-thirds majority needed for ratification. Of the 29 Whig senators, 28 voted against the treaty with only one Whig, a southerner, who supported him. Senate Democrats were more divided on the issue, with six of the Democrats in the North and one Democrat in the South opposing the treaty and five Democrats in the North and South supporting ten Democrats.
Ames K. Polk, a democrat and strong supporter of territorial expansion, was elected president of the United States. in November 1844 with a mandate for the acquisition of both the Republic of Texas and the country of Oregon. After the election, Tyler's government realized that public opinion was in favor of annexation, consulted with President-elect Polk, and set out to comply with the annexation by means of a joint resolution. The resolution established that Texas could be admitted as a state, provided that the annexation was approved before January 1, 1846, which could be divided into four additional states, and that possession of the public lands of the Republic, would pass to the state of Texas after admission. On February 26, 1845, six days before Polk took office, Congress passed the joint resolution. Soon after, Andrew Jackson Donelson, the US charge of business in Texas and the nephew of former President Andrew Jackson, presented the US resolution to President Anson Jones of Texas. On July 4, 1845, the Texas Congress approved the US offer. with only one vote against and began writing a state constitution. The citizens of Texas approved the new Constitution and the annexation ordinance on October 13, 1845, and Polk formally signed the documents integrating Texas into the United States on December 29, 1845.
