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The Nation Expands

Mexican Cession, 1848

After Texas joined the United States in 1846, a boundary dispute broke out almost immediately between the United States and Mexico, the country from which Texas had won its independence a decade earlier. The U.S. said the southern boundary of the state should be the Rio Grande, which was further south of the original boundary set by the Nueces River. On April 25, 1846, after the U.S. cavalry ignored an order from the Mexican army to retreat to the Nueces River and instead advanced south to the Rio Grande, fighting broke out. Three weeks later, Congress declared war on Mexico.

Fighting continued for more than a year, and ended in September 1847. In February 1848, the two countries signed the Treaty of Guadalupe-Hidalgo. The treaty recognized Texas as a U.S. state, and ceded a large chunk of land — about half the area that belonged to the Mexican republic — to the United States for the cost of $15 million. The Mexican Cession included land that would later become California, Nevada, and Utah, as well as portions of Arizona, New Mexico, Colorado, and Wyoming.

The treaty also stated that Mexicans who remained in the state would be permitted to become U. S. citizens, and that they would be allowed to keep their property. However, the treaty was never fully honored. In the decades following the signing of the treaty, Mexican-Americans were stripped of nearly 20 million acres of their land by American businessmen, ranchers and railroad companies, as well as by the U.S. Department of the Interior and Department of Agriculture.

Map of land acquired from the Mexican Cession
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