Texas Annexation
Questions and Answers
Q: What were the boundaries of the Republic of Texas?
A: The boundaries of the Republic of Texas were different from the familiar shape of modern-day Texas.
The eastern boundary of Texas had been set at the Sabine River in 1819 by the Adams-Onís Treaty between the United States and Spain; it was not controversial during the period of the Republic and annexation (though it became the subject of a dispute over oil rights between Louisiana and Texas in the 20th century).
Likewise, the western boundary with the vast desert was of little consequence at the time. The borders to the north and northwest were settled by the Compromise of 1850, in which Texas gave up its claims to vast tracts of western land in exchange for relief for the Republic of Texas debt. (The Red River boundary with Oklahoma, like the Sabine to the east, was the subject of a long-running dispute over oil rights in the 20th century.)
It was the southern border that was the subject of both controversy and bloodshed. During the time of Spanish rule, the boundary between Texas and northern Mexico was variously set at either the Medina or the Nueces River. But in 1836, Texas President David Burnet persuaded General Santa Anna, then a prisoner of war, to sign a treaty promising to withdraw his troops beyond the Rio Grande. This was the beginning of the Texas claim to the Rio Grande as the boundary with Mexico, though the Republic of Texas never actually exercised any control over the Rio Grande Valley. After annexation, United States Army troops under General Zachary Taylor occupied the area. The border issue was finally settled in 1848 by the Treaty of Guadalupe Hidalgo, which ended the Mexican War.