After winning their independence from Mexico in 1836, Texans had voted overwhelmingly in favor of joining the United States. The measure faced opposition in the U.S. Congress, however, where moderates of both parties balked at the prospect of dramatically increasing the size of the southern slave empire. Antislavery societies inundated Congress with petitions opposing the admission of Texas into the Union, and in 1838 former president John Quincy Adams, now a congressman from Braintree, Massachusetts, staged a 22-day filibuster to prevent annexation from coming to a vote. Unwilling to antagonize antislavery Democrats—as well as Mexico, which had vowed to reconquer Texas--the Van Buren administration decided to abandon the measure.
The Texas question lay dormant until 1843, when President John Tyler, a southerner, notified the Texas government that his administration was prepared to renew annexation talks. The two governments drafted an annexation treaty offering to admit the Lone Star republic into the Union as a territory. Once again, Northern Democrats who opposed the expansion of slavery joined with Whigs to defeat the measure in June, 1844. Undaunted, Tyler announced that he would present the issue as a joint resolution, which would require only a simple majority of both houses rather than the two-thirds majority needed for Senate ratification.
The so-called Brown resolution passed during Tyler’s last months in office. The agreement offered Texas better terms than the initial treaty, allowing the republic to enter the Union as a state rather than a territory. The measure passed by a comfortable margin in the House of Representatives but by a narrow 27-25 vote in the Senate. In Texas, a convention ratified the agreement on July 4, and on December 29, 1845 the U.S. Congress accepted the state constitution, upon which Texas entered the Union as the 28th state.
Significantly, the Brown Resolution had left the precise boundaries of Texas undefined, since both Mexico and Texas claimed the land between the Rio Grande and the Nueces River. U.S. expansionist leaders had assumed that some form of compensation would induce Mexico to surrender its claim. However, Tyler’s successor, James K. Polk, accepted the Texas claim, and in the summer of 1845 dispatched U.S. troops to the Rio Grande, thereby setting a chain of events that would lead to war between Mexico and the United States one year later. (For more information, see “The Texas Question.”)