Texas’s path from Mexican province to U.S. state was deeply bound up with slavery, Anglo immigration, and aggressive expansion that ended with a huge U.S. land grab in the Mexican–American War.courses.lumenlearning
After Mexico won independence from Spain in 1821, its government invited U.S. settlers into the province of Coahuila y Tejas under the empresario system, offering cheap land if they became Mexican citizens and Catholics.courses.lumenlearning
Most newcomers were white southerners who brought enslaved Black people and saw Texas as an extension of the cotton South with slavery at its core.studentsofhistory+1
Mexico, increasingly uneasy about this, formally abolished slavery in 1829 under President Vicente Guerrero, which angered many Anglo slaveholders and led to attempts to evade or dilute the law (e.g., re‑labeling enslaved people as “apprentices”).wikipedia+1
Mexico also tried to tighten control by limiting further U.S. immigration, raising tariffs, and reasserting central authority, which Anglo settlers and many local Tejano elites resisted.wikipedia
Tensions exploded in 1835–1836 when many Texians (Anglo settlers and some Tejanos) revolted against the centralizing government of Antonio López de Santa Anna.wikipedia
In February–March 1836, Santa Anna’s roughly 4,000 troops besieged a few hundred Texian defenders in an old mission in San Antonio, the Alamo; after about 10 days, Mexican forces overran the fort and killed nearly all the defenders.courses.lumenlearning
The Alamo soon became a martyr legend in Texian and later U.S. memory (“Remember the Alamo!”), used to rally fighters and later to romanticize a rebellion that had strong pro‑slavery and land‑hunger motives.courses.lumenlearning
A month after the Alamo, at the Battle of San Jacinto (April 1836), Sam Houston’s smaller Texian army surprised and defeated Santa Anna, captured him, and forced him to sign treaties recognizing Texas independence, though Mexico never fully accepted this.wikipedia
The new Republic of Texas (1836–1845) wrote a constitution that explicitly protected slavery, barred free Black people from permanent residence, and encouraged more slaveholding immigration from the U.S. South.courses.lumenlearning+1
Texas claimed a very large area—roughly to the Rio Grande in the south and deep into what is now New Mexico—encompassing land still claimed and inhabited by Mexico and many Native nations.glo.texas
The U.S. hesitated to annex Texas for nearly a decade because it was a large slave republic whose admission threatened the balance between free and slave states and risked war with Mexico.khanacademy+1
In 1845, under the ideology of Manifest Destiny and with strong Southern pressure to expand slave territory, the United States annexed Texas as a slave state.khanacademy
Texas came in claiming the huge Rio Grande boundary; Mexico insisted the real border was the Nueces River, making the intervening region disputed territory.wikipedia
President James K. Polk sent U.S. troops into this disputed zone; fighting broke out in 1846, and Polk used this clash to secure a declaration of war against Mexico, launching the Mexican–American War.wikipedia
U.S. forces invaded from multiple directions, eventually occupying Mexico City; Mexico, militarily defeated and politically fractured, was forced to negotiate.wikipedia
In the 1848 Treaty of Guadalupe Hidalgo, Mexico recognized the Rio Grande as the Texas border and ceded a vast region (present‑day California, Nevada, Utah, most of Arizona, New Mexico, and parts of Colorado and Wyoming), in exchange for a relatively small payment and assumption of some Mexican debts.wikipedia
In effect, a rebellion rooted partly in the desire to protect and expand slavery in Texas became the opening move in a continental land grab that took about half of Mexico’s territory and enormously enlarged the potential area for U.S. slavery’s expansion westward.courses.lumenlearning+1