in Texas, and the republic survived. The cotton price crash of the 1840s depressed the country's economy. Statehood As early as 1837, the Republic of Texas made several attempts to negotiate annexation with the United States. Opposition within the republic from the nationalist faction, along with strong abolitionist opposition within the United States, slowed Texas's admission into the Union. Texas was finally annexed when the expansionist James K. Polk won the election of 1844. On December 29, 1845, the U.S. Congress admitted Texas to the U.S. as a constituent state of the Union. The population of the new state was quite small at first, and there was a strong mix between the English-speaking American settlers who dominated in the state's eastern/northeastern portions and the Spanish-speaking former Mexicans (Tejanos) who dominated in the state's southern and western portions. Statehood brought many new settlers. Because of the long Spanish presence in Mexico and various failed colonization efforts by the Spanish and Mexicans in northern Mexico, there were large herds of Longhorn cattle that roamed the state. Hardy by nature, but also suitable for slaughtering and consumption, they represented an economic opportunity many entrepreneurs seized upon, thus creating the cowboy culture for which Texas is famous. After Texas's annexation, Mexico broke diplomatic relations with the United States. While the United States claimed Texas's border stretched to the Rio Grande, Mexico claimed it was the Nueces River leaving the Rio Grande Valley under contested Texan sovereignty. While the former Republic of Texas could not enforce its border claims, the United States had the military strength and the political will to do so. President Polk ordered General Zachary Taylor south to the Rio Grande on January 13, 1846. A few months later Mexican troops routed an American cavalry patrol in the disputed area in the Thornton Affair starting the Mexican–American War. The first battles of the war were fought in Texas: the Siege of Fort Texas, Battle of Palo Alto and Battle of Resaca de la Palma. After these decisive victories, the United States invaded Mexican territory, ending the fighting in Texas. After a series of United States victories, the Treaty of Guadalupe Hidalgo ended the two-year war. In return, for US$18,250,000, Mexico gave the U.S. undisputed control of Texas, ceded the Mexican Cession in 1848, most of which today is called the American Southwest, and Texas's borders were established at the Rio Grande. The